2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: Eric Sesterhenn 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: [] 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:[] 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] [] ? hfsplus_block_allocate+0x6f/0x2d3 [15840.675016] [] ? hfsplus_file_extend+0xc4/0x1db [15840.675016] [] ? hfsplus_get_block+0x8c/0x19d [15840.675016] [] ? sub_preempt_count+0x9d/0xab [15840.675016] [] ? __block_prepare_write+0x147/0x311 [15840.675016] [] ? __grab_cache_page+0x52/0x73 [15840.675016] [] ? block_write_begin+0x79/0xd5 [15840.675016] [] ? hfsplus_get_block+0x0/0x19d [15840.675016] [] ? cont_write_begin+0x27f/0x2af [15840.675016] [] ? hfsplus_get_block+0x0/0x19d [15840.675016] [] ? tick_program_event+0x28/0x4c [15840.675016] [] ? trace_hardirqs_off+0xb/0xd [15840.675016] [] ? hfsplus_write_begin+0x2d/0x32 [15840.675016] [] ? hfsplus_get_block+0x0/0x19d [15840.675016] [] ? pagecache_write_begin+0x33/0x107 [15840.675016] [] ? __page_symlink+0x3c/0xae [15840.675016] [] ? __mark_inode_dirty+0x12f/0x137 [15840.675016] [] ? page_symlink+0x19/0x1e [15840.675016] [] ? hfsplus_symlink+0x41/0xa6 [15840.675016] [] ? vfs_symlink+0x99/0x101 [15840.675016] [] ? sys_symlinkat+0x6b/0xad [15840.675016] [] ? sys_symlink+0x10/0x12 [15840.675016] [] ? 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: [] 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 Cc: Roman Zippel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/hfsplus/bitmap.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) --- a/fs/hfsplus/bitmap.c +++ b/fs/hfsplus/bitmap.c @@ -32,6 +32,10 @@ int hfsplus_block_allocate(struct super_ 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; @@ -73,6 +77,10 @@ int hfsplus_block_allocate(struct super_ 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; @@ -120,6 +128,10 @@ found: 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; -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/