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ext4: check for directory entries too close to block end

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ext4_check_dir_entry() currently does not catch a case when a directory
entry ends so close to the block end that the header of the next
directory entry would not fit in the remaining space. This can lead to
directory iteration code trying to access address beyond end of current
buffer head leading to oops.

CC: [email protected]
Signed-off-by: Jan Kara <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>
This commit is contained in:
Jan Kara authored and Theodore Ts'o committed 2019-12-14 17:22:45 -05:00
1 parent 64d4ce8923
commit 109ba779d6
1 file changed
+5
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fs/ext4/dir.c
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@@ -81,6 +81,11 @@ int __ext4_check_dir_entry(const char *function, unsigned int line,
error_msg = "rec_len is too small for name_len";
else if (unlikely(((char *) de - buf) + rlen > size))
error_msg = "directory entry overrun";
else if (unlikely(((char *) de - buf) + rlen >
size - EXT4_DIR_REC_LEN(1) &&
((char *) de - buf) + rlen != size)) {
error_msg = "directory entry too close to block end";
}
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";