Submitted By: Jim Gifford Date: 07-15-2009 Initial Package Version: 0.97 Upstream Status: Unknown Origin: Grub Bug Report - http://savannah.gnu.org/bugs/?func=detailitem&item_id=11312 Description: This patch fixes the following issues on x86_64 1) malloc'd pages seem to lack the execute bit on x86_64; 2) grub seems to use some stack pointer diversion to malloc'd pages; 3) nested functions execute data on the stack; 4) this causes a segfault (at least on my machine) diff -Naur grub-0.97.orig/grub/asmstub.c grub-0.97/grub/asmstub.c --- grub-0.97.orig/grub/asmstub.c 2005-02-16 12:45:14.000000000 -0800 +++ grub-0.97/grub/asmstub.c 2009-07-05 23:32:43.000000000 -0700 @@ -42,6 +42,7 @@ #include #include #include +#include #ifdef __linux__ # include /* ioctl */ @@ -79,7 +80,7 @@ struct apm_info apm_bios_info; /* Emulation requirements. */ -char *grub_scratch_mem = 0; +void *grub_scratch_mem = 0; struct geometry *disks = 0; @@ -103,14 +104,62 @@ static unsigned int serial_speed; #endif /* SIMULATE_SLOWNESS_OF_SERIAL */ +/* This allocates page-aligned storage of the specified size, which must be + * a multiple of the page size as determined by calling sysconf(_SC_PAGESIZE) + */ +#ifdef __linux__ +static void * +grub_mmap_alloc(size_t len) +{ + int mmap_flags = MAP_ANONYMOUS|MAP_PRIVATE; + +#ifdef MAP_32BIT + mmap_flags |= MAP_32BIT; +#endif + /* Mark the simulated stack executable, as GCC uses stack trampolines + * to implement nested functions. */ + return mmap(NULL, len, PROT_READ|PROT_WRITE|PROT_EXEC, mmap_flags, -1, 0); +} +#else /* !defined(__linux__) */ +static void * +grub_mmap_alloc(size_t len) +{ + int fd = 0, offset = 0, ret = 0; + void *pa = MAP_FAILED; + char template[] = "/tmp/grub_mmap_alloc_XXXXXX"; + int e; + + fd = mkstemp(template); + if (fd < 0) + return pa; + + unlink(template); + + ret = ftruncate(fd, len); + if (ret < 0) + return pa; + + /* Mark the simulated stack executable, as GCC uses stack trampolines + * to implement nested functions. */ + pa = mmap(NULL, len, PROT_READ|PROT_WRITE|PROT_EXEC, + MAP_PRIVATE, fd, offset); + + e = errno; + close(fd); + errno = e; + return pa; +} +#endif /* defined(__linux__) */ + /* The main entry point into this mess. */ int grub_stage2 (void) { /* These need to be static, because they survive our stack transitions. */ static int status = 0; - static char *realstack; - char *scratch, *simstack; + static void *realstack; + void *simstack_alloc_base, *simstack; + size_t simstack_size, page_size; int i; auto void doit (void); @@ -142,9 +191,35 @@ } assert (grub_scratch_mem == 0); - scratch = malloc (0x100000 + EXTENDED_MEMSIZE + 15); - assert (scratch); - grub_scratch_mem = (char *) ((((int) scratch) >> 4) << 4); + + /* Allocate enough pages for 0x100000 + EXTENDED_SIZE + 15, and + * make sure the memory is aligned to a multiple of the system's + * page size */ + page_size = sysconf (_SC_PAGESIZE); + simstack_size = ( 0x100000 + EXTENDED_MEMSIZE + 15); + if (simstack_size % page_size) + { + /* If we're not on a page_size boundary, round up to the next one */ + simstack_size &= ~(page_size-1); + simstack_size += page_size; + } + + /* Add one for a PROT_NONE boundary page at each end. */ + simstack_size += 2 * page_size; + + simstack_alloc_base = grub_mmap_alloc(simstack_size); + assert (simstack_alloc_base != MAP_FAILED); + + /* mark pages above and below our simstack area as innaccessable. + * If the implementation we're using doesn't support that, then the + * new protection modes are undefined. It's safe to just ignore + * them, though. It'd be nice if we knew that we'd get a SEGV for + * touching the area, but that's all. it'd be nice to have. */ + mprotect (simstack_alloc_base, page_size, PROT_NONE); + mprotect ((void *)((unsigned long)simstack_alloc_base + + simstack_size - page_size), page_size, PROT_NONE); + + grub_scratch_mem = (void *)((unsigned long)simstack_alloc_base + page_size); /* FIXME: simulate the memory holes using mprot, if available. */ @@ -217,7 +292,7 @@ device_map = 0; free (disks); disks = 0; - free (scratch); + munmap(simstack_alloc_base, simstack_size); grub_scratch_mem = 0; if (serial_device) diff -Naur grub-0.97.orig/stage2/builtins.c grub-0.97/stage2/builtins.c --- grub-0.97.orig/stage2/builtins.c 2005-02-15 13:58:23.000000000 -0800 +++ grub-0.97/stage2/builtins.c 2009-07-05 23:42:45.000000000 -0700 @@ -130,63 +130,97 @@ grub_printf ("[%d,%d,%d]", sector, offset, length); } - +/* blocklist_read_helper nee disk_read_blocklist_func was a nested + * function, to which pointers were taken and exposed globally. Even + * in the GNU-C nested functions extension, they have local linkage, + * and aren't guaranteed to be accessable *at all* outside of their + * containing scope. + * + * Above and beyond all of that, the variables within blocklist_func_context + * are originally local variables, with local (not even static) linkage, + * from within blocklist_func. These were each referenced by + * disk_read_blocklist_func, which is only called from other functions + * through a globally scoped pointer. + * + * The documentation in GCC actually uses the words "all hell will break + * loose" to describe this scenario. + * + * Also, "start_sector" was also used uninitialized, but gcc doesn't warn + * about it (possibly because of the scoping madness?) + */ + +static struct { + int start_sector; + int num_sectors; + int num_entries; + int last_length; +} blocklist_func_context = { + .start_sector = 0, + .num_sectors = 0, + .num_entries = 0, + .last_length = 0 +}; + +/* Collect contiguous blocks into one entry as many as possible, + and print the blocklist notation on the screen. */ +static void +blocklist_read_helper (int sector, int offset, int length) +{ + int *start_sector = &blocklist_func_context.start_sector; + int *num_sectors = &blocklist_func_context.num_sectors; + int *num_entries = &blocklist_func_context.num_entries; + int *last_length = &blocklist_func_context.last_length; + + if (*num_sectors > 0) + { + if (*start_sector + *num_sectors == sector + && offset == 0 && *last_length == SECTOR_SIZE) + { + *num_sectors++; + *last_length = length; + return; + } + else + { + if (*last_length == SECTOR_SIZE) + grub_printf ("%s%d+%d", *num_entries ? "," : "", + *start_sector - part_start, *num_sectors); + else if (*num_sectors > 1) + grub_printf ("%s%d+%d,%d[0-%d]", *num_entries ? "," : "", + *start_sector - part_start, *num_sectors-1, + *start_sector + *num_sectors-1 - part_start, + *last_length); + else + grub_printf ("%s%d[0-%d]", *num_entries ? "," : "", + *start_sector - part_start, *last_length); + *num_entries++; + *num_sectors = 0; + } + } + + if (offset > 0) + { + grub_printf("%s%d[%d-%d]", *num_entries ? "," : "", + sector-part_start, offset, offset+length); + *num_entries++; + } + else + { + *start_sector = sector; + *num_sectors = 1; + *last_length = length; + } +} + /* blocklist */ static int blocklist_func (char *arg, int flags) { char *dummy = (char *) RAW_ADDR (0x100000); - int start_sector; - int num_sectors = 0; - int num_entries = 0; - int last_length = 0; - auto void disk_read_blocklist_func (int sector, int offset, int length); - - /* Collect contiguous blocks into one entry as many as possible, - and print the blocklist notation on the screen. */ - auto void disk_read_blocklist_func (int sector, int offset, int length) - { - if (num_sectors > 0) - { - if (start_sector + num_sectors == sector - && offset == 0 && last_length == SECTOR_SIZE) - { - num_sectors++; - last_length = length; - return; - } - else - { - if (last_length == SECTOR_SIZE) - grub_printf ("%s%d+%d", num_entries ? "," : "", - start_sector - part_start, num_sectors); - else if (num_sectors > 1) - grub_printf ("%s%d+%d,%d[0-%d]", num_entries ? "," : "", - start_sector - part_start, num_sectors-1, - start_sector + num_sectors-1 - part_start, - last_length); - else - grub_printf ("%s%d[0-%d]", num_entries ? "," : "", - start_sector - part_start, last_length); - num_entries++; - num_sectors = 0; - } - } - - if (offset > 0) - { - grub_printf("%s%d[%d-%d]", num_entries ? "," : "", - sector-part_start, offset, offset+length); - num_entries++; - } - else - { - start_sector = sector; - num_sectors = 1; - last_length = length; - } - } + int *start_sector = &blocklist_func_context.start_sector; + int *num_sectors = &blocklist_func_context.num_sectors; + int *num_entries = &blocklist_func_context.num_entries; /* Open the file. */ if (! grub_open (arg)) @@ -206,15 +240,15 @@ grub_printf (")"); /* Read in the whole file to DUMMY. */ - disk_read_hook = disk_read_blocklist_func; + disk_read_hook = blocklist_read_helper; if (! grub_read (dummy, -1)) goto fail; /* The last entry may not be printed yet. Don't check if it is a * full sector, since it doesn't matter if we read too much. */ - if (num_sectors > 0) - grub_printf ("%s%d+%d", num_entries ? "," : "", - start_sector - part_start, num_sectors); + if (*num_sectors > 0) + grub_printf ("%s%d+%d", *num_entries ? "," : "", + *start_sector - part_start, *num_sectors); grub_printf ("\n"); @@ -1740,6 +1774,77 @@ /* install */ +static struct { + int saved_sector; + int installaddr; + int installlist; + char *stage2_first_buffer; +} install_func_context = { + .saved_sector = 0, + .installaddr = 0, + .installlist = 0, + .stage2_first_buffer = NULL, +}; + +/* Save the first sector of Stage2 in STAGE2_SECT. */ +/* Formerly disk_read_savesect_func with local scope inside install_func */ +static void +install_savesect_helper(int sector, int offset, int length) +{ + if (debug) + printf ("[%d]", sector); + + /* ReiserFS has files which sometimes contain data not aligned + on sector boundaries. Returning an error is better than + silently failing. */ + if (offset != 0 || length != SECTOR_SIZE) + errnum = ERR_UNALIGNED; + + install_func_context.saved_sector = sector; +} + +/* Write SECTOR to INSTALLLIST, and update INSTALLADDR and INSTALLSECT. */ +/* Formerly disk_read_blocklist_func with local scope inside install_func */ +static void +install_blocklist_helper (int sector, int offset, int length) +{ + int *installaddr = &install_func_context.installaddr; + int *installlist = &install_func_context.installlist; + char **stage2_first_buffer = &install_func_context.stage2_first_buffer; + /* Was the last sector full? */ + static int last_length = SECTOR_SIZE; + + if (debug) + printf("[%d]", sector); + + if (offset != 0 || last_length != SECTOR_SIZE) + { + /* We found a non-sector-aligned data block. */ + errnum = ERR_UNALIGNED; + return; + } + + last_length = length; + + if (*((unsigned long *) (*installlist - 4)) + + *((unsigned short *) *installlist) != sector + || *installlist == (int) *stage2_first_buffer + SECTOR_SIZE + 4) + { + *installlist -= 8; + + if (*((unsigned long *) (*installlist - 8))) + errnum = ERR_WONT_FIT; + else + { + *((unsigned short *) (*installlist + 2)) = (*installaddr >> 4); + *((unsigned long *) (*installlist - 4)) = sector; + } + } + + *((unsigned short *) *installlist) += 1; + *installaddr += 512; +} + static int install_func (char *arg, int flags) { @@ -1747,8 +1852,12 @@ char *stage1_buffer = (char *) RAW_ADDR (0x100000); char *stage2_buffer = stage1_buffer + SECTOR_SIZE; char *old_sect = stage2_buffer + SECTOR_SIZE; - char *stage2_first_buffer = old_sect + SECTOR_SIZE; - char *stage2_second_buffer = stage2_first_buffer + SECTOR_SIZE; + /* stage2_first_buffer used to be defined as: + * char *stage2_first_buffer = old_sect + SECTOR_SIZE; */ + char **stage2_first_buffer = &install_func_context.stage2_first_buffer; + /* and stage2_second_buffer was: + * char *stage2_second_buffer = stage2_first_buffer + SECTOR_SIZE; */ + char *stage2_second_buffer = old_sect + SECTOR_SIZE + SECTOR_SIZE; /* XXX: Probably SECTOR_SIZE is reasonable. */ char *config_filename = stage2_second_buffer + SECTOR_SIZE; char *dummy = config_filename + SECTOR_SIZE; @@ -1757,10 +1866,11 @@ int src_drive, src_partition, src_part_start; int i; struct geometry dest_geom, src_geom; - int saved_sector; + int *saved_sector = &install_func_context.saved_sector; int stage2_first_sector, stage2_second_sector; char *ptr; - int installaddr, installlist; + int *installaddr = &install_func_context.installaddr; + int *installlist = &install_func_context.installlist; /* Point to the location of the name of a configuration file in Stage 2. */ char *config_file_location; /* If FILE is a Stage 1.5? */ @@ -1769,67 +1879,13 @@ int is_open = 0; /* If LBA is forced? */ int is_force_lba = 0; - /* Was the last sector full? */ - int last_length = SECTOR_SIZE; - + + *stage2_first_buffer = old_sect + SECTOR_SIZE; #ifdef GRUB_UTIL /* If the Stage 2 is in a partition mounted by an OS, this will store the filename under the OS. */ char *stage2_os_file = 0; #endif /* GRUB_UTIL */ - - auto void disk_read_savesect_func (int sector, int offset, int length); - auto void disk_read_blocklist_func (int sector, int offset, int length); - - /* Save the first sector of Stage2 in STAGE2_SECT. */ - auto void disk_read_savesect_func (int sector, int offset, int length) - { - if (debug) - printf ("[%d]", sector); - - /* ReiserFS has files which sometimes contain data not aligned - on sector boundaries. Returning an error is better than - silently failing. */ - if (offset != 0 || length != SECTOR_SIZE) - errnum = ERR_UNALIGNED; - - saved_sector = sector; - } - - /* Write SECTOR to INSTALLLIST, and update INSTALLADDR and - INSTALLSECT. */ - auto void disk_read_blocklist_func (int sector, int offset, int length) - { - if (debug) - printf("[%d]", sector); - - if (offset != 0 || last_length != SECTOR_SIZE) - { - /* We found a non-sector-aligned data block. */ - errnum = ERR_UNALIGNED; - return; - } - - last_length = length; - - if (*((unsigned long *) (installlist - 4)) - + *((unsigned short *) installlist) != sector - || installlist == (int) stage2_first_buffer + SECTOR_SIZE + 4) - { - installlist -= 8; - - if (*((unsigned long *) (installlist - 8))) - errnum = ERR_WONT_FIT; - else - { - *((unsigned short *) (installlist + 2)) = (installaddr >> 4); - *((unsigned long *) (installlist - 4)) = sector; - } - } - - *((unsigned short *) installlist) += 1; - installaddr += 512; - } /* First, check the GNU-style long option. */ while (1) @@ -1862,10 +1918,10 @@ addr = skip_to (0, file); /* Get the installation address. */ - if (! safe_parse_maxint (&addr, &installaddr)) + if (! safe_parse_maxint (&addr, installaddr)) { /* ADDR is not specified. */ - installaddr = 0; + *installaddr = 0; ptr = addr; errnum = 0; } @@ -1961,17 +2017,17 @@ = 0x9090; /* Read the first sector of Stage 2. */ - disk_read_hook = disk_read_savesect_func; - if (grub_read (stage2_first_buffer, SECTOR_SIZE) != SECTOR_SIZE) + disk_read_hook = install_savesect_helper; + if (grub_read (*stage2_first_buffer, SECTOR_SIZE) != SECTOR_SIZE) goto fail; - stage2_first_sector = saved_sector; + stage2_first_sector = *saved_sector; /* Read the second sector of Stage 2. */ if (grub_read (stage2_second_buffer, SECTOR_SIZE) != SECTOR_SIZE) goto fail; - stage2_second_sector = saved_sector; + stage2_second_sector = *saved_sector; /* Check for the version of Stage 2. */ if (*((short *) (stage2_second_buffer + STAGE2_VER_MAJ_OFFS)) @@ -1987,27 +2043,27 @@ /* If INSTALLADDR is not specified explicitly in the command-line, determine it by the Stage 2 id. */ - if (! installaddr) + if (! *installaddr) { if (! is_stage1_5) /* Stage 2. */ - installaddr = 0x8000; + *installaddr = 0x8000; else /* Stage 1.5. */ - installaddr = 0x2000; + *installaddr = 0x2000; } *((unsigned long *) (stage1_buffer + STAGE1_STAGE2_SECTOR)) = stage2_first_sector; *((unsigned short *) (stage1_buffer + STAGE1_STAGE2_ADDRESS)) - = installaddr; + = *installaddr; *((unsigned short *) (stage1_buffer + STAGE1_STAGE2_SEGMENT)) - = installaddr >> 4; + = *installaddr >> 4; - i = (int) stage2_first_buffer + SECTOR_SIZE - 4; + i = (int) *stage2_first_buffer + SECTOR_SIZE - 4; while (*((unsigned long *) i)) { - if (i < (int) stage2_first_buffer + if (i < (int) *stage2_first_buffer || (*((int *) (i - 4)) & 0x80000000) || *((unsigned short *) i) >= 0xA00 || *((short *) (i + 2)) == 0) @@ -2021,13 +2077,13 @@ i -= 8; } - installlist = (int) stage2_first_buffer + SECTOR_SIZE + 4; - installaddr += SECTOR_SIZE; + *installlist = (int) *stage2_first_buffer + SECTOR_SIZE + 4; + *installaddr += SECTOR_SIZE; /* Read the whole of Stage2 except for the first sector. */ grub_seek (SECTOR_SIZE); - disk_read_hook = disk_read_blocklist_func; + disk_read_hook = install_blocklist_helper; if (! grub_read (dummy, -1)) goto fail; @@ -2110,7 +2166,7 @@ /* Skip the first sector. */ grub_seek (SECTOR_SIZE); - disk_read_hook = disk_read_savesect_func; + disk_read_hook = install_savesect_helper; if (grub_read (stage2_buffer, SECTOR_SIZE) != SECTOR_SIZE) goto fail; @@ -2180,7 +2236,7 @@ else #endif /* GRUB_UTIL */ { - if (! devwrite (saved_sector - part_start, 1, stage2_buffer)) + if (! devwrite (*saved_sector - part_start, 1, stage2_buffer)) goto fail; } } @@ -2202,7 +2258,7 @@ goto fail; } - if (fwrite (stage2_first_buffer, 1, SECTOR_SIZE, fp) != SECTOR_SIZE) + if (fwrite (*stage2_first_buffer, 1, SECTOR_SIZE, fp) != SECTOR_SIZE) { fclose (fp); errnum = ERR_WRITE; @@ -2229,7 +2285,7 @@ goto fail; if (! devwrite (stage2_first_sector - src_part_start, 1, - stage2_first_buffer)) + *stage2_first_buffer)) goto fail; if (! devwrite (stage2_second_sector - src_part_start, 1, diff -Naur grub-0.97.orig/stage2/shared.h grub-0.97/stage2/shared.h --- grub-0.97.orig/stage2/shared.h 2004-06-19 09:40:09.000000000 -0700 +++ grub-0.97/stage2/shared.h 2009-07-05 23:32:43.000000000 -0700 @@ -36,8 +36,8 @@ /* Maybe redirect memory requests through grub_scratch_mem. */ #ifdef GRUB_UTIL -extern char *grub_scratch_mem; -# define RAW_ADDR(x) ((x) + (int) grub_scratch_mem) +extern void *grub_scratch_mem; +# define RAW_ADDR(x) ((x) + (unsigned long) grub_scratch_mem) # define RAW_SEG(x) (RAW_ADDR ((x) << 4) >> 4) #else # define RAW_ADDR(x) (x)