Syzkaller reported a UBSAN bug below, which was mainly caused by a large negative number passed to the timeout of the io_getevents system call. ====================================================================== UBSAN: Undefined behaviour in ./include/linux/ktime.h:42:14 signed integer overflow: -8427032702788048137 * 1000000000 cannot be represented in type 'long long int' CPU: 3 PID: 11668 Comm: syz-executor0 Not tainted 4.19.18-514.55.6.9.x86_64+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xca/0x13e lib/dump_stack.c:113 ubsan_epilogue+0xe/0x81 lib/ubsan.c:159 handle_overflow+0x193/0x1e2 lib/ubsan.c:190 ktime_set include/linux/ktime.h:42 [inline] timespec64_to_ktime include/linux/ktime.h:78 [inline] do_io_getevents+0x307/0x390 fs/aio.c:2043 __do_sys_io_getevents fs/aio.c:2080 [inline] __se_sys_io_getevents fs/aio.c:2068 [inline] __x64_sys_io_getevents+0x163/0x250 fs/aio.c:2068 do_syscall_64+0xc8/0x580 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x462589 Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fde9b04ec58 EFLAGS: 00000246 ORIG_RAX: 00000000000000d0 RAX: ffffffffffffffda RBX: 000000000072bf00 RCX: 0000000000462589 RDX: 0000000000000006 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000005 R08: 0000000020000100 R09: 0000000000000000 R10: 0000000020000040 R11: 0000000000000246 R12: 00007fde9b04f6bc R13: 00000000004bd1f0 R14: 00000000006f6b60 R15: 00000000ffffffff ====================================================================== bond0 (unregistering): Released all slaves The timeout described in "man io_getevents" does not say whether it can be negative or not, but as a waiting time, a negative number has no meaning. So I add check to avoid this case. This issue was previously discussed at: https://lore.kernel.org/lkml/CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@xxxxxxxxxxxxxx/ Signed-off-by: Tan Xiaojun <tanxiaojun@xxxxxxxxxx> Reviewed-by: Jeff Moyer <jmoyer@xxxxxxxxxx> --- fs/aio.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index aaaaf4d..3a39673 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -2078,10 +2078,16 @@ static long do_io_getevents(aio_context_t ctx_id, struct io_event __user *events, struct timespec64 *ts) { - ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX; - struct kioctx *ioctx = lookup_ioctx(ctx_id); + ktime_t until; + struct kioctx *ioctx; long ret = -EINVAL; + if (ts && !timespec64_valid(ts)) + return -EINVAL; + + until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX; + ioctx = lookup_ioctx(ctx_id); + if (likely(ioctx)) { if (likely(min_nr <= nr && min_nr >= 0)) ret = read_events(ioctx, min_nr, nr, events, until); -- 2.7.4
