Messages in this thread | | | From | Dmitry Vyukov <> | Date | Wed, 22 Jun 2022 09:39:39 +0200 | Subject | Re: [syzbot] memory leak in setup_mq_sysctls |
| |
On Wed, 22 Jun 2022 at 00:41, Alexey Gladkov <legion@kernel.org> wrote: > > On Tue, Jun 21, 2022 at 09:30:57AM -0500, Eric W. Biederman wrote: > > Alexey Gladkov <gladkov.alexey@gmail.com> writes: > > > > > On Sun, Jun 19, 2022 at 11:52:25PM -0700, syzbot wrote: > > >> Hello, > > >> > > >> syzbot found the following issue on: > > >> > > >> HEAD commit: 979086f5e006 Merge tag 'fs.fixes.v5.19-rc3' of git://git.k.. > > >> git tree: upstream > > >> console output: https://syzkaller.appspot.com/x/log.txt?x=1284331bf00000 > > >> kernel config: https://syzkaller.appspot.com/x/.config?x=c696a83383a77f81 > > >> dashboard link: https://syzkaller.appspot.com/bug?extid=b4b0d1b35442afbf6fd2 > > >> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=163e740ff00000 > > >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=132b758bf00000 > > >> > > >> IMPORTANT: if you fix the issue, please add the following tag to the commit: > > >> Reported-by: syzbot+b4b0d1b35442afbf6fd2@syzkaller.appspotmail.com > > > > > > I'm working on a fix that will remove this memory allocation entirely. > > > > Hmm. The memory should be freed when the corresponding namespace exits. > > I see retire_mq_sysctls is being called to free this memory. Alex do > > you see any leaks when you read that code? > > I don't see a leak either. retire_mq_sysctls and retire_ipc_sysctls > functions are identical and are called one by one. I don't understand how > there can be an mq leak without an ipc leak. Unless it has something to do > with mq_init_ns (just guess).
Are they feed on this error path: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/ipc/namespace.c?id=979086f5e0066b4eff66e1eee123da228489985c#n64 ? I don't see where it calls retire_mq_sysctls.
> > So it looks like either someone broke this in linux-next or there > > is a bug in the memory leak detector, or something truly strange > > like a memory stop is going on. > > I will take a look. > > > I don't see any changes to the ipc subdirectory since v5.19-rc1 in > > commit 979086f5e006 ("Merge tag 'fs.fixes.v5.19-rc3' of git://git.k.." ) > > so the idea that the code is broken in linux-next is out. > > > > Which leaves the memory leak detector having trouble with this, > > or something like a memory stomp is causing problems. > > > > Catalin is it possible that the clever use of ctl_table_arg to hold the > > reference to the table before it is freed is confusing the memory leak > > detector? The idiom is old enough I don't expect so, but I have seen > > bugs lurk for a long time. > > > > Which leaves just a memory stomp or something even stranger in the code. > > syzkaller can you reproduce this on Linus's branch? > > > > Eric > > > > >> executing program > > >> BUG: memory leak > > >> unreferenced object 0xffff888112fc9200 (size 512): > > >> comm "syz-executor237", pid 3648, jiffies 4294970469 (age 12.270s) > > >> hex dump (first 32 bytes): > > >> ef d3 60 85 ff ff ff ff 0c 9b d2 12 81 88 ff ff ..`............. > > >> 04 00 00 00 a4 01 00 00 00 00 00 00 00 00 00 00 ................ > > >> backtrace: > > >> [<ffffffff814b6eb3>] kmemdup+0x23/0x50 mm/util.c:129 > > >> [<ffffffff82219a9b>] kmemdup include/linux/fortify-string.h:456 [inline] > > >> [<ffffffff82219a9b>] setup_mq_sysctls+0x4b/0x1c0 ipc/mq_sysctl.c:89 > > >> [<ffffffff822197f2>] create_ipc_ns ipc/namespace.c:63 [inline] > > >> [<ffffffff822197f2>] copy_ipcs+0x292/0x390 ipc/namespace.c:91 > > >> [<ffffffff8127de7c>] create_new_namespaces+0xdc/0x4f0 kernel/nsproxy.c:90 > > >> [<ffffffff8127e89b>] unshare_nsproxy_namespaces+0x9b/0x120 kernel/nsproxy.c:226 > > >> [<ffffffff8123f92e>] ksys_unshare+0x2fe/0x600 kernel/fork.c:3165 > > >> [<ffffffff8123fc42>] __do_sys_unshare kernel/fork.c:3236 [inline] > > >> [<ffffffff8123fc42>] __se_sys_unshare kernel/fork.c:3234 [inline] > > >> [<ffffffff8123fc42>] __x64_sys_unshare+0x12/0x20 kernel/fork.c:3234 > > >> [<ffffffff845aab45>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > >> [<ffffffff845aab45>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > >> [<ffffffff8460006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0 > > >> > > >> BUG: memory leak > > >> unreferenced object 0xffff888112fd5f00 (size 256): > > >> comm "syz-executor237", pid 3648, jiffies 4294970469 (age 12.270s) > > >> hex dump (first 32 bytes): > > >> 00 92 fc 12 81 88 ff ff 00 00 00 00 01 00 00 00 ................ > > >> 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > > >> backtrace: > > >> [<ffffffff816fea1b>] kmalloc include/linux/slab.h:605 [inline] > > >> [<ffffffff816fea1b>] kzalloc include/linux/slab.h:733 [inline] > > >> [<ffffffff816fea1b>] __register_sysctl_table+0x7b/0x7f0 fs/proc/proc_sysctl.c:1344 > > >> [<ffffffff82219b7a>] setup_mq_sysctls+0x12a/0x1c0 ipc/mq_sysctl.c:112 > > >> [<ffffffff822197f2>] create_ipc_ns ipc/namespace.c:63 [inline] > > >> [<ffffffff822197f2>] copy_ipcs+0x292/0x390 ipc/namespace.c:91 > > >> [<ffffffff8127de7c>] create_new_namespaces+0xdc/0x4f0 kernel/nsproxy.c:90 > > >> [<ffffffff8127e89b>] unshare_nsproxy_namespaces+0x9b/0x120 kernel/nsproxy.c:226 > > >> [<ffffffff8123f92e>] ksys_unshare+0x2fe/0x600 kernel/fork.c:3165 > > >> [<ffffffff8123fc42>] __do_sys_unshare kernel/fork.c:3236 [inline] > > >> [<ffffffff8123fc42>] __se_sys_unshare kernel/fork.c:3234 [inline] > > >> [<ffffffff8123fc42>] __x64_sys_unshare+0x12/0x20 kernel/fork.c:3234 > > >> [<ffffffff845aab45>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > >> [<ffffffff845aab45>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > >> [<ffffffff8460006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0 > > >> > > >> BUG: memory leak > > >> unreferenced object 0xffff888112fbba00 (size 256): > > >> comm "syz-executor237", pid 3648, jiffies 4294970469 (age 12.270s) > > >> hex dump (first 32 bytes): > > >> 78 ba fb 12 81 88 ff ff 00 00 00 00 01 00 00 00 x............... > > >> 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > > >> backtrace: > > >> [<ffffffff816fef49>] kmalloc include/linux/slab.h:605 [inline] > > >> [<ffffffff816fef49>] kzalloc include/linux/slab.h:733 [inline] > > >> [<ffffffff816fef49>] new_dir fs/proc/proc_sysctl.c:978 [inline] > > >> [<ffffffff816fef49>] get_subdir fs/proc/proc_sysctl.c:1022 [inline] > > >> [<ffffffff816fef49>] __register_sysctl_table+0x5a9/0x7f0 fs/proc/proc_sysctl.c:1373 > > >> [<ffffffff82219b7a>] setup_mq_sysctls+0x12a/0x1c0 ipc/mq_sysctl.c:112 > > >> [<ffffffff822197f2>] create_ipc_ns ipc/namespace.c:63 [inline] > > >> [<ffffffff822197f2>] copy_ipcs+0x292/0x390 ipc/namespace.c:91 > > >> [<ffffffff8127de7c>] create_new_namespaces+0xdc/0x4f0 kernel/nsproxy.c:90 > > >> [<ffffffff8127e89b>] unshare_nsproxy_namespaces+0x9b/0x120 kernel/nsproxy.c:226 > > >> [<ffffffff8123f92e>] ksys_unshare+0x2fe/0x600 kernel/fork.c:3165 > > >> [<ffffffff8123fc42>] __do_sys_unshare kernel/fork.c:3236 [inline] > > >> [<ffffffff8123fc42>] __se_sys_unshare kernel/fork.c:3234 [inline] > > >> [<ffffffff8123fc42>] __x64_sys_unshare+0x12/0x20 kernel/fork.c:3234 > > >> [<ffffffff845aab45>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > >> [<ffffffff845aab45>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > >> [<ffffffff8460006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0 > > >> > > >> BUG: memory leak > > >> unreferenced object 0xffff888112fbb900 (size 256): > > >> comm "syz-executor237", pid 3648, jiffies 4294970469 (age 12.270s) > > >> hex dump (first 32 bytes): > > >> 78 b9 fb 12 81 88 ff ff 00 00 00 00 01 00 00 00 x............... > > >> 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > > >> backtrace: > > >> [<ffffffff816fef49>] kmalloc include/linux/slab.h:605 [inline] > > >> [<ffffffff816fef49>] kzalloc include/linux/slab.h:733 [inline] > > >> [<ffffffff816fef49>] new_dir fs/proc/proc_sysctl.c:978 [inline] > > >> [<ffffffff816fef49>] get_subdir fs/proc/proc_sysctl.c:1022 [inline] > > >> [<ffffffff816fef49>] __register_sysctl_table+0x5a9/0x7f0 fs/proc/proc_sysctl.c:1373 > > >> [<ffffffff82219b7a>] setup_mq_sysctls+0x12a/0x1c0 ipc/mq_sysctl.c:112 > > >> [<ffffffff822197f2>] create_ipc_ns ipc/namespace.c:63 [inline] > > >> [<ffffffff822197f2>] copy_ipcs+0x292/0x390 ipc/namespace.c:91 > > >> [<ffffffff8127de7c>] create_new_namespaces+0xdc/0x4f0 kernel/nsproxy.c:90 > > >> [<ffffffff8127e89b>] unshare_nsproxy_namespaces+0x9b/0x120 kernel/nsproxy.c:226 > > >> [<ffffffff8123f92e>] ksys_unshare+0x2fe/0x600 kernel/fork.c:3165 > > >> [<ffffffff8123fc42>] __do_sys_unshare kernel/fork.c:3236 [inline] > > >> [<ffffffff8123fc42>] __se_sys_unshare kernel/fork.c:3234 [inline] > > >> [<ffffffff8123fc42>] __x64_sys_unshare+0x12/0x20 kernel/fork.c:3234 > > >> [<ffffffff845aab45>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > >> [<ffffffff845aab45>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > >> [<ffffffff8460006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0 > > >> > > >> > > >> > > >> --- > > >> This report is generated by a bot. It may contain errors. > > >> See https://goo.gl/tpsmEJ for more information about syzbot. > > >> syzbot engineers can be reached at syzkaller@googlegroups.com. > > >> > > >> syzbot will keep track of this issue. See: > > >> https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > >> syzbot can test patches for this issue, for details see: > > >> https://goo.gl/tpsmEJ#testing-patches
| |