squashfs: add more sanity checks in xattr id lookup

Sysbot has reported a warning where a kmalloc() attempt exceeds the
maximum limit.  This has been identified as corruption of the xattr_ids
count when reading the xattr id lookup table.

This patch adds a number of additional sanity checks to detect this
corruption and others.

1. It checks for a corrupted xattr index read from the inode.  This could
   be because the metadata block is uncompressed, or because the
   "compression" bit has been corrupted (turning a compressed block
   into an uncompressed block).  This would cause an out of bounds read.

2. It checks against corruption of the xattr_ids count.  This can either
   lead to the above kmalloc failure, or a smaller than expected
   table to be read.

3. It checks the contents of the index table for corruption.

[[email protected]: fix checkpatch issue]
  Link: https://lkml.kernel.org/r/[email protected]

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Phillip Lougher <[email protected]>
Reported-by: [email protected]
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions