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| author | Qu Wenruo <wqu@suse.com> | 2017-11-06 10:43:18 +0800 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2017-11-27 17:01:11 +0100 |
| commit | eae8d82529dd9820e206ecba0047b806c4410e65 (patch) | |
| tree | 4ffa64543581d15ddabb694d74ca272e0ec220fa /fs | |
| parent | b77000ed558daa3bef0899d29bf171b8c9b5e6a8 (diff) | |
| download | linux-eae8d82529dd9820e206ecba0047b806c4410e65.tar.gz linux-eae8d82529dd9820e206ecba0047b806c4410e65.tar.bz2 linux-eae8d82529dd9820e206ecba0047b806c4410e65.zip | |
btrfs: Fix wild memory access in compression level parser
[BUG]
Kernel panic when mounting with "-o compress" mount option.
KASAN will report like:
------
==================================================================
BUG: KASAN: wild-memory-access in strncmp+0x31/0xc0
Read of size 1 at addr d86735fce994f800 by task mount/662
...
Call Trace:
dump_stack+0xe3/0x175
kasan_report+0x163/0x370
__asan_load1+0x47/0x50
strncmp+0x31/0xc0
btrfs_compress_str2level+0x20/0x70 [btrfs]
btrfs_parse_options+0xff4/0x1870 [btrfs]
open_ctree+0x2679/0x49f0 [btrfs]
btrfs_mount+0x1b7f/0x1d30 [btrfs]
mount_fs+0x49/0x190
vfs_kern_mount.part.29+0xba/0x280
vfs_kern_mount+0x13/0x20
btrfs_mount+0x31e/0x1d30 [btrfs]
mount_fs+0x49/0x190
vfs_kern_mount.part.29+0xba/0x280
do_mount+0xaad/0x1a00
SyS_mount+0x98/0xe0
entry_SYSCALL_64_fastpath+0x1f/0xbe
------
[Cause]
For 'compress' and 'compress_force' options, its token doesn't expect
any parameter so its args[0] contains uninitialized data.
Accessing args[0] will cause above wild memory access.
[Fix]
For Opt_compress and Opt_compress_force, set compression level to
the default.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ set the default in advance ]
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/compression.c | 2 | ||||
| -rw-r--r-- | fs/btrfs/compression.h | 2 | ||||
| -rw-r--r-- | fs/btrfs/super.c | 13 |
3 files changed, 14 insertions, 3 deletions
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index 4a78e5726337..5982c8a71f02 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -1529,5 +1529,5 @@ unsigned int btrfs_compress_str2level(const char *str) if (str[4] == ':' && '1' <= str[5] && str[5] <= '9' && str[6] == 0) return str[5] - '0'; - return 0; + return BTRFS_ZLIB_DEFAULT_LEVEL; } diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h index 93c5b82ae97e..0868cc554f14 100644 --- a/fs/btrfs/compression.h +++ b/fs/btrfs/compression.h @@ -34,6 +34,8 @@ /* Maximum size of data before compression */ #define BTRFS_MAX_UNCOMPRESSED (SZ_128K) +#define BTRFS_ZLIB_DEFAULT_LEVEL 3 + struct compressed_bio { /* number of bios pending for this compressed extent */ refcount_t pending_bios; diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 65af029559b5..ff3545e526f5 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -507,9 +507,18 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options, token == Opt_compress_force || strncmp(args[0].from, "zlib", 4) == 0) { compress_type = "zlib"; + info->compress_type = BTRFS_COMPRESS_ZLIB; - info->compress_level = - btrfs_compress_str2level(args[0].from); + info->compress_level = BTRFS_ZLIB_DEFAULT_LEVEL; + /* + * args[0] contains uninitialized data since + * for these tokens we don't expect any + * parameter. + */ + if (token != Opt_compress && + token != Opt_compress_force) + info->compress_level = + btrfs_compress_str2level(args[0].from); btrfs_set_opt(info->mount_opt, COMPRESS); btrfs_clear_opt(info->mount_opt, NODATACOW); btrfs_clear_opt(info->mount_opt, NODATASUM); |