Re: UBSAN: shift-out-of-bounds in xprt_do_reserve

On 2/9/21 5:24 PM, syzbot wrote:

Hello,

syzbot found the following issue on:

HEAD commit:    dd86e7fa Merge tag 'pci-v5.11-fixes-2' of git://git.kernel..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=105930c4d00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=266a5362c89c8127
dashboard link: https://syzkaller.appspot.com/bug?extid=f3a0fa110fd630ab56c8
compiler:       Debian clang version 11.0.1-2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17ba3038d00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15cf0d64d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f3a0fa110fd630ab56c8@syzkaller.appspotmail.com

#syz dup: UBSAN: shift-out-of-bounds in xprt_calc_majortimeo

================================================================================
UBSAN: shift-out-of-bounds in net/sunrpc/xprt.c:658:14
shift exponent 536870976 is too large for 64-bit type 'unsigned long'
CPU: 1 PID: 8411 Comm: syz-executor902 Not tainted 5.11.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x137/0x1be lib/dump_stack.c:120
 ubsan_epilogue lib/ubsan.c:148 [inline]
 __ubsan_handle_shift_out_of_bounds+0x432/0x4d0 lib/ubsan.c:395
 xprt_calc_majortimeo net/sunrpc/xprt.c:658 [inline]
 xprt_init_majortimeo net/sunrpc/xprt.c:686 [inline]

-- 
~Randy