fs/squashfs: fix integer overflow in directory table allocation

sqfs_read_directory_table() allocates the directory table with
malloc(metablks_count * SQFS_METADATA_BLOCK_SIZE). metablks_count is an
int and SQFS_METADATA_BLOCK_SIZE is 8192, so the multiply is evaluated in
int and wraps for metablks_count >= 2^19. metablks_count comes from the
attacker-controlled superblock (sqfs_count_metablks() grows it by one per
2-byte metadata header), so a crafted image under-allocates the buffer
while the fill loop still writes metablks_count metadata blocks into it,
a heap out-of-bounds write. It is reached by listing or reading the image
(sqfsls / sqfsload). The position list allocation on the next line has the
same unchecked-multiply shape.

Size both allocations with __builtin_mul_overflow() and reject the image
on overflow, as the disk-read buffers earlier in the same function already
do. Set the error return when either allocation fails so the caller does
not proceed with a NULL directory table.

Fixes: c51006130370 ("fs/squashfs: new filesystem")
Signed-off-by: Shahriyar Jalayeri <[email protected]>
Reviewed-by: Richard Genoud <[email protected]>

0 files changed, 0 insertions, 0 deletions