On Wed, 20 May 2020 11:21:00 +0300 vitaly.wool@xxxxxxxxxxxx wrote: > From: Uladzislau Rezki <uladzislau.rezki@xxxxxxxx> > > free_handle() for a foreign handle may race with inter-page > compaction, what can lead to memory corruption. To avoid that, > take write lock not read lock in free_handle to be synchronized > with __release_z3fold_page(). > > For example KASAN can detect it: > > [ 33.723357] ================================================================== > [ 33.723401] BUG: KASAN: use-after-free in LZ4_decompress_safe+0x2c4/0x3b8 > [ 33.723418] Read of size 1 at addr ffffffc976695ca3 by task GoogleApiHandle/4121 > [ 33.723428] > [ 33.723449] CPU: 0 PID: 4121 Comm: GoogleApiHandle Tainted: P S OE 4.19.81-perf+ #162 > [ 33.723461] Hardware name: Sony Mobile Communications. PDX-203(KONA) (DT) > [ 33.723473] Call trace: > [ 33.723495] dump_backtrace+0x0/0x288 > [ 33.723512] show_stack+0x14/0x20 > [ 33.723533] dump_stack+0xe4/0x124 > [ 33.723551] print_address_description+0x80/0x2e0 > [ 33.723566] kasan_report+0x268/0x2d0 > [ 33.723584] __asan_load1+0x4c/0x58 > [ 33.723601] LZ4_decompress_safe+0x2c4/0x3b8 > [ 33.723619] lz4_decompress_crypto+0x3c/0x70 > [ 33.723636] crypto_decompress+0x58/0x70 > [ 33.723656] zcomp_decompress+0xd4/0x120 > ... > > Apart from that, initialize zhdr->mapped_count in init_z3fold_page() > and remove "newpage" variable because it is not used anywhere. > > Signed-off-by: Uladzislau Rezki <uladzislau.rezki@xxxxxxxx> > Signed-off-by: Vitaly Wool <vitaly.wool@xxxxxxxxxxxx> I assume that a cc:stable is appropriate here?
