On Thu, May 21, 2020 at 2:46 AM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > 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? Absolutely. stable was in fact in CC: but it didn't reflect in the patch for some reason. Thanks! ~Vitaly
