Commit 109ba779 authored by Jan Kara's avatar Jan Kara Committed by Theodore Ts'o

ext4: check for directory entries too close to block end

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: stable@vger.kernel.org
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20191202170213.4761-3-jack@suse.czSigned-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 64d4ce89
...@@ -81,6 +81,11 @@ int __ext4_check_dir_entry(const char *function, unsigned int line, ...@@ -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"; error_msg = "rec_len is too small for name_len";
else if (unlikely(((char *) de - buf) + rlen > size)) else if (unlikely(((char *) de - buf) + rlen > size))
error_msg = "directory entry overrun"; 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) > else if (unlikely(le32_to_cpu(de->inode) >
le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))) le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
error_msg = "inode out of bounds"; error_msg = "inode out of bounds";
......
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