From: Breno Leitao <leitao@xxxxxxxxxx> > Sent: 05 June 2024 09:55 > > There is a potential out-of-bounds access when using test_bit() on a > single word. The test_bit() and set_bit() functions operate on long > values, and when testing or setting a single word, they can exceed the > word boundary. KASAN detects this issue and produces a dump: > > BUG: KASAN: slab-out-of-bounds in _scsih_add_device.constprop.0 > (./arch/x86/include/asm/bitops.h:60 ./include/asm-generic/bitops/instrumented-atomic.h:29 > drivers/scsi/mpt3sas/mpt3sas_scsih.c:7331) mpt3sas > > Write of size 8 at addr ffff8881d26e3c60 by task kworker/u1536:2/2965 > > For full log, please look at [1]. > > Make the allocation at least the size of sizeof(unsigned long) so that > set_bit() and test_bit() have sufficient room for read/write operations > without overwriting unallocated memory. > ... > @@ -8512,6 +8512,12 @@ mpt3sas_base_attach(struct MPT3SAS_ADAPTER *ioc) > ioc->pd_handles_sz = (ioc->facts.MaxDevHandle / 8); > if (ioc->facts.MaxDevHandle % 8) > ioc->pd_handles_sz++; > + /* pd_handles_sz should have, at least, the minimal room > + * for set_bit()/test_bit(), otherwise out-of-memory touch > + * may occur > + */ > + ioc->pd_handles_sz = ALIGN(ioc->pd_handles_sz, sizeof(unsigned long)); > + > ioc->pd_handles = kzalloc(ioc->pd_handles_sz, > GFP_KERNEL); That is entirely stupid code. IIRC there is a BITMAP_SIZE() that does ((x) + 63u) & ~63)/8 (on 64bit systems). David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
