On 2/10/22 9:11 AM, Willy Tarreau wrote:
On Wed, Feb 09, 2022 at 10:08:07PM -0800, syzbot wrote:syzbot has bisected this issue to: commit 7661809d493b426e979f39ab512e3adf41fbcc69 Author: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Date: Wed Jul 14 16:45:49 2021 +0000 mm: don't allow oversized kvmalloc() calls bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13bc74c2700000 start commit: f4bc5bbb5fef Merge tag 'nfsd-5.17-2' of git://git.kernel.o.. git tree: upstream final oops: https://syzkaller.appspot.com/x/report.txt?x=107c74c2700000 console output: https://syzkaller.appspot.com/x/log.txt?x=17bc74c2700000 kernel config: https://syzkaller.appspot.com/x/.config?x=5707221760c00a20 dashboard link: https://syzkaller.appspot.com/bug?extid=11421fbbff99b989670e syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12e514a4700000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15fcdf8a700000 Reported-by: syzbot+11421fbbff99b989670e@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 7661809d493b ("mm: don't allow oversized kvmalloc() calls") For information about bisection process see: https://goo.gl/tpsmEJ#bisectionInteresting, so in fact syzkaller has shown that the aforementioned patch does its job well and has spotted a call path by which a single userland setsockopt() can request more than 2 GB allocation in the kernel. Most likely that's in fact what needs to be addressed. FWIW the call trace at the URL above is: Call Trace: kvmalloc include/linux/mm.h:806 [inline] kvmalloc_array include/linux/mm.h:824 [inline] kvcalloc include/linux/mm.h:829 [inline] xdp_umem_pin_pages net/xdp/xdp_umem.c:102 [inline] xdp_umem_reg net/xdp/xdp_umem.c:219 [inline] xdp_umem_create+0x6a5/0xf00 net/xdp/xdp_umem.c:252 xsk_setsockopt+0x604/0x790 net/xdp/xsk.c:1068 __sys_setsockopt+0x1fd/0x4e0 net/socket.c:2176 __do_sys_setsockopt net/socket.c:2187 [inline] __se_sys_setsockopt net/socket.c:2184 [inline] __x64_sys_setsockopt+0xb5/0x150 net/socket.c:2184 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae and the meaningful part of the repro is: syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul); syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul); syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul); intptr_t res = 0; res = syscall(__NR_socket, 0x2cul, 3ul, 0); if (res != -1) r[0] = res; *(uint64_t*)0x20000080 = 0; *(uint64_t*)0x20000088 = 0xfff02000000; *(uint32_t*)0x20000090 = 0x800; *(uint32_t*)0x20000094 = 0; *(uint32_t*)0x20000098 = 0; syscall(__NR_setsockopt, r[0], 0x11b, 4, 0x20000080ul, 0x20ul);
Bjorn had a comment back then when the issue was first raised here: https://lore.kernel.org/bpf/3f854ca9-f5d6-4065-c7b1-5e5b25ea742f@xxxxxxxxxxxxx/ There was earlier discussion from Andrew to potentially retire the warning: https://lore.kernel.org/bpf/20211201202905.b9892171e3f5b9a60f9da251@xxxxxxxxxxxxxxxxxxxx/ Bjorn / Magnus / Andrew, anyone planning to follow-up on this issue? Thanks, Daniel
