forked from Minki/linux
fa520c47ea
fscache_set_key() can incur an out-of-bounds read, reported by KASAN:
BUG: KASAN: slab-out-of-bounds in fscache_alloc_cookie+0x5b3/0x680 [fscache]
Read of size 4 at addr ffff88084ff056d4 by task mount.nfs/32615
and also reported by syzbot at https://lkml.org/lkml/2018/7/8/236
BUG: KASAN: slab-out-of-bounds in fscache_set_key fs/fscache/cookie.c:120 [inline]
BUG: KASAN: slab-out-of-bounds in fscache_alloc_cookie+0x7a9/0x880 fs/fscache/cookie.c:171
Read of size 4 at addr ffff8801d3cc8bb4 by task syz-executor907/4466
This happens for any index_key_len which is not divisible by 4 and is
larger than the size of the inline key, because the code allocates exactly
index_key_len for the key buffer, but the hashing loop is stepping through
it 4 bytes (u32) at a time in the buf[] array.
Fix this by calculating how many u32 buffers we'll need by using
DIV_ROUND_UP, and then using kcalloc() to allocate a precleared allocation
buffer to hold the index_key, then using that same count as the hashing
index limit.
Fixes:
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||
|---|---|---|
| .. | ||
| cache.c | ||
| cookie.c | ||
| fsdef.c | ||
| histogram.c | ||
| internal.h | ||
| Kconfig | ||
| main.c | ||
| Makefile | ||
| netfs.c | ||
| object-list.c | ||
| object.c | ||
| operation.c | ||
| page.c | ||
| proc.c | ||
| stats.c | ||