On Tue, Dec 20, 2016 at 11:35:23PM +0100, Andrey Konovalov wrote: > On Tue, Dec 20, 2016 at 10:01 PM, Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote: > > On Tue, Dec 20, 2016 at 03:43:27PM +0100, Andrey Konovalov wrote: > >> Hi, > >> > >> I've got the following warning while running the syzkaller fuzzer: > >> > >> WARNING: unrecognized kernel stack return address ffffffffa0000001 at > >> ffff88006377fa18 in a.out:4467 > >> > >> By adding a BUG() to unwind_get_return_address() I was able to capture > >> the stack trace (see below). Looks like unwind_get_return_address() > >> gets called when KASAN tries to unwind the stack to save the stack > >> trace. > >> > >> A reproducer is attached. CONFIG_KASAN=y is most likely needed for it to work. > > > > Hi Andrey, > > > > I've tried with your reproducer but it didn't recreate. Can you try > > again with the following patch from the tip tree, instead of your BUG() > > patch? > > > > http://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/patch/?id=8b5e99f02264130782a10ba5c0c759797fb064ee > > > > That will dump the stack data, which should give more clues about what > > went wrong. > > Hi Josh, > > Sure, here it is: Thanks. Looking at the stack trace, my guess is that an interrupt hit while running in generated BPF code, and the unwinder got confused because regs->ip points to the generated code. I may need to disable that warning until we figure out a better solution. Can you share your .config file? -- Josh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>