diff options
| author | Sergei Trofimovich <slyich@gmail.com> | 2011-04-11 21:52:52 +0000 |
|---|---|---|
| committer | Chris Mason <chris.mason@oracle.com> | 2011-04-11 20:25:06 -0400 |
| commit | 3387206f26e1b48703e810175b98611a4fd8e8ea (patch) | |
| tree | 501460ae54271ab8872606b9aef0bc3ab2ec5bc0 /fs/btrfs/extent_io.c | |
| parent | 8fb27640d0e2b43c5584bf0087431b7b8d3c319a (diff) | |
btrfs: properly handle overlapping areas in memmove_extent_buffer
Fix data corruption caused by memcpy() usage on overlapping data.
I've observed it first when found out usermode linux crash on btrfs.
?all chain is the following:
------------[ cut here ]------------
WARNING: at /home/slyfox/linux-2.6/fs/btrfs/extent_io.c:3900 memcpy_extent_buffer+0x1a5/0x219()
Call Trace:
6fa39a58: [<601b495e>] _raw_spin_unlock_irqrestore+0x18/0x1c
6fa39a68: [<60029ad9>] warn_slowpath_common+0x59/0x70
6fa39aa8: [<60029b05>] warn_slowpath_null+0x15/0x17
6fa39ab8: [<600efc97>] memcpy_extent_buffer+0x1a5/0x219
6fa39b48: [<600efd9f>] memmove_extent_buffer+0x94/0x208
6fa39bc8: [<600becbf>] btrfs_del_items+0x214/0x473
6fa39c78: [<600ce1b0>] btrfs_delete_one_dir_name+0x7c/0xda
6fa39cc8: [<600dad6b>] __btrfs_unlink_inode+0xad/0x25d
6fa39d08: [<600d7864>] btrfs_start_transaction+0xe/0x10
6fa39d48: [<600dc9ff>] btrfs_unlink_inode+0x1b/0x3b
6fa39d78: [<600e04bc>] btrfs_unlink+0x70/0xef
6fa39dc8: [<6007f0d0>] vfs_unlink+0x58/0xa3
6fa39df8: [<60080278>] do_unlinkat+0xd4/0x162
6fa39e48: [<600517db>] call_rcu_sched+0xe/0x10
6fa39e58: [<600452a8>] __put_cred+0x58/0x5a
6fa39e78: [<6007446c>] sys_faccessat+0x154/0x166
6fa39ed8: [<60080317>] sys_unlink+0x11/0x13
6fa39ee8: [<60016b80>] handle_syscall+0x58/0x70
6fa39f08: [<60021377>] userspace+0x2d4/0x381
6fa39fc8: [<60014507>] fork_handler+0x62/0x69
---[ end trace 70b0ca2ef0266b93 ]---
http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg09302.html
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Reviewed-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/extent_io.c')
| -rw-r--r-- | fs/btrfs/extent_io.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 77c65a0bea3..864e0496cc1 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3885,6 +3885,12 @@ static void move_pages(struct page *dst_page, struct page *src_page, kunmap_atomic(dst_kaddr, KM_USER0); } +static inline bool areas_overlap(unsigned long src, unsigned long dst, unsigned long len) +{ + unsigned long distance = (src > dst) ? src - dst : dst - src; + return distance < len; +} + static void copy_pages(struct page *dst_page, struct page *src_page, unsigned long dst_off, unsigned long src_off, unsigned long len) @@ -3892,10 +3898,12 @@ static void copy_pages(struct page *dst_page, struct page *src_page, char *dst_kaddr = kmap_atomic(dst_page, KM_USER0); char *src_kaddr; - if (dst_page != src_page) + if (dst_page != src_page) { src_kaddr = kmap_atomic(src_page, KM_USER1); - else + } else { src_kaddr = dst_kaddr; + BUG_ON(areas_overlap(src_off, dst_off, len)); + } memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len); kunmap_atomic(dst_kaddr, KM_USER0); @@ -3970,7 +3978,7 @@ void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset, "len %lu len %lu\n", dst_offset, len, dst->len); BUG_ON(1); } - if (dst_offset < src_offset) { + if (!areas_overlap(src_offset, dst_offset, len)) { memcpy_extent_buffer(dst, dst_offset, src_offset, len); return; } |