linux/fs/hfsplus/bitmap.c
Eric Sesterhenn 649f1ee6c7 hfsplus: check read_mapping_page() return value
While testing more corrupted images with hfsplus, i came across
one which triggered the following bug:

[15840.675016] BUG: unable to handle kernel paging request at fffffffb
[15840.675016] IP: [<c0116a4f>] kmap+0x15/0x56
[15840.675016] *pde = 00008067 *pte = 00000000
[15840.675016] Oops: 0000 [#1] PREEMPT DEBUG_PAGEALLOC
[15840.675016] Modules linked in:
[15840.675016]
[15840.675016] Pid: 11575, comm: ln Not tainted (2.6.27-rc4-00123-gd3ee1b4-dirty #29)
[15840.675016] EIP: 0060:[<c0116a4f>] EFLAGS: 00010202 CPU: 0
[15840.675016] EIP is at kmap+0x15/0x56
[15840.675016] EAX: 00000246 EBX: fffffffb ECX: 00000000 EDX: cab919c0
[15840.675016] ESI: 000007dd EDI: cab0bcf4 EBP: cab0bc98 ESP: cab0bc94
[15840.675016]  DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
[15840.675016] Process ln (pid: 11575, ti=cab0b000 task=cab919c0 task.ti=cab0b000)
[15840.675016] Stack: 00000000 cab0bcdc c0231cfb 00000000 cab0bce0 00000800 ca9290c0 fffffffb
[15840.675016]        cab145d0 cab919c0 cab15998 22222222 22222222 22222222 00000001 cab15960
[15840.675016]        000007dd cab0bcf4 cab0bd04 c022cb3a cab0bcf4 cab15a6c ca9290c0 00000000
[15840.675016] Call Trace:
[15840.675016]  [<c0231cfb>] ? hfsplus_block_allocate+0x6f/0x2d3
[15840.675016]  [<c022cb3a>] ? hfsplus_file_extend+0xc4/0x1db
[15840.675016]  [<c022ce41>] ? hfsplus_get_block+0x8c/0x19d
[15840.675016]  [<c06adde4>] ? sub_preempt_count+0x9d/0xab
[15840.675016]  [<c019ece6>] ? __block_prepare_write+0x147/0x311
[15840.675016]  [<c0161934>] ? __grab_cache_page+0x52/0x73
[15840.675016]  [<c019ef4f>] ? block_write_begin+0x79/0xd5
[15840.675016]  [<c022cdb5>] ? hfsplus_get_block+0x0/0x19d
[15840.675016]  [<c019f22a>] ? cont_write_begin+0x27f/0x2af
[15840.675016]  [<c022cdb5>] ? hfsplus_get_block+0x0/0x19d
[15840.675016]  [<c0139ebe>] ? tick_program_event+0x28/0x4c
[15840.675016]  [<c013bd35>] ? trace_hardirqs_off+0xb/0xd
[15840.675016]  [<c022b723>] ? hfsplus_write_begin+0x2d/0x32
[15840.675016]  [<c022cdb5>] ? hfsplus_get_block+0x0/0x19d
[15840.675016]  [<c0161988>] ? pagecache_write_begin+0x33/0x107
[15840.675016]  [<c01879e5>] ? __page_symlink+0x3c/0xae
[15840.675016]  [<c019ad34>] ? __mark_inode_dirty+0x12f/0x137
[15840.675016]  [<c0187a70>] ? page_symlink+0x19/0x1e
[15840.675016]  [<c022e6eb>] ? hfsplus_symlink+0x41/0xa6
[15840.675016]  [<c01886a9>] ? vfs_symlink+0x99/0x101
[15840.675016]  [<c018a2f6>] ? sys_symlinkat+0x6b/0xad
[15840.675016]  [<c018a348>] ? sys_symlink+0x10/0x12
[15840.675016]  [<c01038bd>] ? sysenter_do_call+0x12/0x31
[15840.675016]  =======================
[15840.675016] Code: 00 00 75 10 83 3d 88 2f ec c0 02 75 07 89 d0 e8 12 56 05 00 5d c3 55 ba 06 00 00 00 89 e5 53 89 c3 b8 3d eb 7e c0 e8 16 74 00 00 <8b> 03 c1 e8 1e 69 c0 d8 02 00 00 05 b8 69 8e c0 2b 80 c4 02 00
[15840.675016] EIP: [<c0116a4f>] kmap+0x15/0x56 SS:ESP 0068:cab0bc94
[15840.675016] ---[ end trace 4fea40dad6b70e5f ]---

This happens because the return value of read_mapping_page() is passed on
to kmap unchecked.  The bug is triggered after the first
read_mapping_page() in hfsplus_block_allocate(), this patch fixes all
three usages in this functions but leaves the ones further down in the
file unchanged.

Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-16 11:21:46 -07:00

232 lines
4.8 KiB
C

/*
* linux/fs/hfsplus/bitmap.c
*
* Copyright (C) 2001
* Brad Boyer (flar@allandria.com)
* (C) 2003 Ardis Technologies <roman@ardistech.com>
*
* Handling of allocation file
*/
#include <linux/pagemap.h>
#include "hfsplus_fs.h"
#include "hfsplus_raw.h"
#define PAGE_CACHE_BITS (PAGE_CACHE_SIZE * 8)
int hfsplus_block_allocate(struct super_block *sb, u32 size, u32 offset, u32 *max)
{
struct page *page;
struct address_space *mapping;
__be32 *pptr, *curr, *end;
u32 mask, start, len, n;
__be32 val;
int i;
len = *max;
if (!len)
return size;
dprint(DBG_BITMAP, "block_allocate: %u,%u,%u\n", size, offset, len);
mutex_lock(&HFSPLUS_SB(sb).alloc_file->i_mutex);
mapping = HFSPLUS_SB(sb).alloc_file->i_mapping;
page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL);
if (IS_ERR(page)) {
start = size;
goto out;
}
pptr = kmap(page);
curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
i = offset % 32;
offset &= ~(PAGE_CACHE_BITS - 1);
if ((size ^ offset) / PAGE_CACHE_BITS)
end = pptr + PAGE_CACHE_BITS / 32;
else
end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
/* scan the first partial u32 for zero bits */
val = *curr;
if (~val) {
n = be32_to_cpu(val);
mask = (1U << 31) >> i;
for (; i < 32; mask >>= 1, i++) {
if (!(n & mask))
goto found;
}
}
curr++;
/* scan complete u32s for the first zero bit */
while (1) {
while (curr < end) {
val = *curr;
if (~val) {
n = be32_to_cpu(val);
mask = 1 << 31;
for (i = 0; i < 32; mask >>= 1, i++) {
if (!(n & mask))
goto found;
}
}
curr++;
}
kunmap(page);
offset += PAGE_CACHE_BITS;
if (offset >= size)
break;
page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
NULL);
if (IS_ERR(page)) {
start = size;
goto out;
}
curr = pptr = kmap(page);
if ((size ^ offset) / PAGE_CACHE_BITS)
end = pptr + PAGE_CACHE_BITS / 32;
else
end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
}
dprint(DBG_BITMAP, "bitmap full\n");
start = size;
goto out;
found:
start = offset + (curr - pptr) * 32 + i;
if (start >= size) {
dprint(DBG_BITMAP, "bitmap full\n");
goto out;
}
/* do any partial u32 at the start */
len = min(size - start, len);
while (1) {
n |= mask;
if (++i >= 32)
break;
mask >>= 1;
if (!--len || n & mask)
goto done;
}
if (!--len)
goto done;
*curr++ = cpu_to_be32(n);
/* do full u32s */
while (1) {
while (curr < end) {
n = be32_to_cpu(*curr);
if (len < 32)
goto last;
if (n) {
len = 32;
goto last;
}
*curr++ = cpu_to_be32(0xffffffff);
len -= 32;
}
set_page_dirty(page);
kunmap(page);
offset += PAGE_CACHE_BITS;
page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
NULL);
if (IS_ERR(page)) {
start = size;
goto out;
}
pptr = kmap(page);
curr = pptr;
end = pptr + PAGE_CACHE_BITS / 32;
}
last:
/* do any partial u32 at end */
mask = 1U << 31;
for (i = 0; i < len; i++) {
if (n & mask)
break;
n |= mask;
mask >>= 1;
}
done:
*curr = cpu_to_be32(n);
set_page_dirty(page);
kunmap(page);
*max = offset + (curr - pptr) * 32 + i - start;
HFSPLUS_SB(sb).free_blocks -= *max;
sb->s_dirt = 1;
dprint(DBG_BITMAP, "-> %u,%u\n", start, *max);
out:
mutex_unlock(&HFSPLUS_SB(sb).alloc_file->i_mutex);
return start;
}
int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count)
{
struct page *page;
struct address_space *mapping;
__be32 *pptr, *curr, *end;
u32 mask, len, pnr;
int i;
/* is there any actual work to be done? */
if (!count)
return 0;
dprint(DBG_BITMAP, "block_free: %u,%u\n", offset, count);
/* are all of the bits in range? */
if ((offset + count) > HFSPLUS_SB(sb).total_blocks)
return -2;
mutex_lock(&HFSPLUS_SB(sb).alloc_file->i_mutex);
mapping = HFSPLUS_SB(sb).alloc_file->i_mapping;
pnr = offset / PAGE_CACHE_BITS;
page = read_mapping_page(mapping, pnr, NULL);
pptr = kmap(page);
curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
end = pptr + PAGE_CACHE_BITS / 32;
len = count;
/* do any partial u32 at the start */
i = offset % 32;
if (i) {
int j = 32 - i;
mask = 0xffffffffU << j;
if (j > count) {
mask |= 0xffffffffU >> (i + count);
*curr++ &= cpu_to_be32(mask);
goto out;
}
*curr++ &= cpu_to_be32(mask);
count -= j;
}
/* do full u32s */
while (1) {
while (curr < end) {
if (count < 32)
goto done;
*curr++ = 0;
count -= 32;
}
if (!count)
break;
set_page_dirty(page);
kunmap(page);
page = read_mapping_page(mapping, ++pnr, NULL);
pptr = kmap(page);
curr = pptr;
end = pptr + PAGE_CACHE_BITS / 32;
}
done:
/* do any partial u32 at end */
if (count) {
mask = 0xffffffffU >> count;
*curr &= cpu_to_be32(mask);
}
out:
set_page_dirty(page);
kunmap(page);
HFSPLUS_SB(sb).free_blocks += len;
sb->s_dirt = 1;
mutex_unlock(&HFSPLUS_SB(sb).alloc_file->i_mutex);
return 0;
}