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| author | Theodore Ts'o <tytso@mit.edu> | 2018-08-27 15:22:45 +0200 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2018-08-27 15:22:45 +0200 |
| commit | 4d982e25d0bdc83d8c64e66fdeca0b89240b3b85 (patch) | |
| tree | f1775363ff05e10010530d4fc5a2201f7fae02d6 /fs/ext4/dir.c | |
| parent | ext4: check to make sure the rename(2)'s destination is not freed (diff) | |
| download | linux-4d982e25d0bdc83d8c64e66fdeca0b89240b3b85.tar.xz linux-4d982e25d0bdc83d8c64e66fdeca0b89240b3b85.zip | |
ext4: avoid divide by zero fault when deleting corrupted inline directories
A specially crafted file system can trick empty_inline_dir() into
reading past the last valid entry in a inline directory, and then run
into the end of xattr marker. This will trigger a divide by zero
fault. Fix this by using the size of the inline directory instead of
dir->i_size.
Also clean up error reporting in __ext4_check_dir_entry so that the
message is clearer and more understandable --- and avoids the division
by zero trap if the size passed in is zero. (I'm not sure why we
coded it that way in the first place; printing offset % size is
actually more confusing and less useful.)
https://bugzilla.kernel.org/show_bug.cgi?id=200933
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reported-by: Wen Xu <wen.xu@gatech.edu>
Cc: stable@vger.kernel.org
Diffstat (limited to 'fs/ext4/dir.c')
| -rw-r--r-- | fs/ext4/dir.c | 20 |
1 files changed, 9 insertions, 11 deletions
diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c index e2902d394f1b..f93f9881ec18 100644 --- a/fs/ext4/dir.c +++ b/fs/ext4/dir.c @@ -76,7 +76,7 @@ int __ext4_check_dir_entry(const char *function, unsigned int line, else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len))) error_msg = "rec_len is too small for name_len"; else if (unlikely(((char *) de - buf) + rlen > size)) - error_msg = "directory entry across range"; + error_msg = "directory entry overrun"; else if (unlikely(le32_to_cpu(de->inode) > le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))) error_msg = "inode out of bounds"; @@ -85,18 +85,16 @@ int __ext4_check_dir_entry(const char *function, unsigned int line, if (filp) ext4_error_file(filp, function, line, bh->b_blocknr, - "bad entry in directory: %s - offset=%u(%u), " - "inode=%u, rec_len=%d, name_len=%d", - error_msg, (unsigned) (offset % size), - offset, le32_to_cpu(de->inode), - rlen, de->name_len); + "bad entry in directory: %s - offset=%u, " + "inode=%u, rec_len=%d, name_len=%d, size=%d", + error_msg, offset, le32_to_cpu(de->inode), + rlen, de->name_len, size); else ext4_error_inode(dir, function, line, bh->b_blocknr, - "bad entry in directory: %s - offset=%u(%u), " - "inode=%u, rec_len=%d, name_len=%d", - error_msg, (unsigned) (offset % size), - offset, le32_to_cpu(de->inode), - rlen, de->name_len); + "bad entry in directory: %s - offset=%u, " + "inode=%u, rec_len=%d, name_len=%d, size=%d", + error_msg, offset, le32_to_cpu(de->inode), + rlen, de->name_len, size); return 1; } |