On Sat, 2023-01-28 at 23:37 +0100, Andrey Konovalov wrote: > /On Sat, Jan 28, 2023 at 4:00 PM Kuan-Ying Lee > <Kuan-Ying.Lee@xxxxxxxxxxxx> wrote: > > > > From: Andrey Konovalov <andreyknvl@xxxxxxxxxx> > > Ah, I think you need to reset the commit author before sending, so > that the patch gets recorded as authored by you. Got it. Will do in v4. > > Make KASAN scan metadata to infer the requested allocation size > > instead of > > printing cache->object_size. > > > > This patch fixes confusing slab-out-of-bounds reports as reported > > in: > > > > https://urldefense.com/v3/__https://bugzilla.kernel.org/show_bug.cgi?id=216457__;!!CTRNKA9wMg0ARbw!mXW4Z05dX9YXnBYWxw-OOBYutqBM0JFoaApK61lFCSldptsVi0JEtWNSU9uaSnXbGq5oiKCBfyHLFFtEmY5uFgDl$ ; > > > > > > As an example of the confusing behavior, the report below hints > > that the > > allocation size was 192, while the kernel actually called > > kmalloc(184): > > > > ================================================================== > > BUG: KASAN: slab-out-of-bounds in _find_next_bit+0x143/0x160 > > lib/find_bit.c:109 > > Read of size 8 at addr ffff8880175766b8 by task kworker/1:1/26 > > ... > > The buggy address belongs to the object at ffff888017576600 > > which belongs to the cache kmalloc-192 of size 192 > > The buggy address is located 184 bytes inside of > > 192-byte region [ffff888017576600, ffff8880175766c0) > > ... > > Memory state around the buggy address: > > ffff888017576580: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc > > ffff888017576600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > ffff888017576680: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc > > > > ^ > > ffff888017576700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > > ffff888017576780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > > ================================================================== > > > > With this patch, the report shows: > > > > ================================================================== > > ... > > The buggy address belongs to the object at ffff888017576600 > > which belongs to the cache kmalloc-192 of size 192 > > The buggy address is located 0 bytes to the right of > > allocated 184-byte region [ffff888017576600, ffff8880175766b8) > > ... > > ================================================================== > > > > Also report slab use-after-free bugs as "slab-use-after-free" and > > print > > "freed" instead of "allocated" in the report when describing the > > accessed > > memory region. > > > > Also improve the metadata-related comment in > > kasan_find_first_bad_addr > > and use addr_has_metadata across KASAN code instead of open-coding > > KASAN_SHADOW_START checks. > > > > Link: > > https://urldefense.com/v3/__https://bugzilla.kernel.org/show_bug.cgi?id=216457__;!!CTRNKA9wMg0ARbw!mXW4Z05dX9YXnBYWxw-OOBYutqBM0JFoaApK61lFCSldptsVi0JEtWNSU9uaSnXbGq5oiKCBfyHLFFtEmY5uFgDl$ ; > > > > Co-developed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx> > > Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@xxxxxxxxxxxx> > > Or change the Co-developed-by/Signed-off-by tags. > > I don't mind either approach. > > Thanks!
