* Re: general protection fault in override_creds [not found] <000000000000da160a0598b2c704@google.com> @ 2019-12-02 6:40 ` Dmitry Vyukov 2019-12-02 15:40 ` Jens Axboe 2019-12-02 15:22 ` syzbot 1 sibling, 1 reply; 4+ messages in thread From: Dmitry Vyukov @ 2019-12-02 6:40 UTC (permalink / raw) To: syzbot, Jens Axboe, Al Viro, io-uring, linux-fsdevel Cc: Anna.Schumaker, Casey Schaufler, David Howells, Jann Horn, Kees Cook, Kate Stewart, LKML, NeilBrown, syzkaller-bugs, Thomas Gleixner On Mon, Dec 2, 2019 at 7:35 AM syzbot <syzbot+5320383e16029ba057ff@syzkaller.appspotmail.com> wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: b94ae8ad Merge tag 'seccomp-v5.5-rc1' of git://git.kernel... > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=10f9ffcee00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=ff560c3de405258c > dashboard link: https://syzkaller.appspot.com/bug?extid=5320383e16029ba057ff > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12dd682ae00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16290abce00000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+5320383e16029ba057ff@syzkaller.appspotmail.com I think this relates to fs/io_uring.c rather than kernel/cred.c. +io_uring maintainers > kasan: CONFIG_KASAN_INLINE enabled > kasan: GPF could be caused by NULL-ptr deref or user memory access > general protection fault: 0000 [#1] PREEMPT SMP KASAN > CPU: 0 PID: 9217 Comm: io_uring-sq Not tainted 5.4.0-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > RIP: 0010:creds_are_invalid kernel/cred.c:792 [inline] > RIP: 0010:__validate_creds include/linux/cred.h:187 [inline] > RIP: 0010:override_creds+0x9f/0x170 kernel/cred.c:550 > Code: ac 25 00 81 fb 64 65 73 43 0f 85 a3 37 00 00 e8 17 ab 25 00 49 8d 7c > 24 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 > c0 74 08 3c 03 0f 8e 96 00 00 00 41 8b 5c 24 10 bf > RSP: 0018:ffff88809c45fda0 EFLAGS: 00010202 > RAX: dffffc0000000000 RBX: 0000000043736564 RCX: ffffffff814f3318 > RDX: 0000000000000002 RSI: ffffffff814f3329 RDI: 0000000000000010 > RBP: ffff88809c45fdb8 R08: ffff8880a3aac240 R09: ffffed1014755849 > R10: ffffed1014755848 R11: ffff8880a3aac247 R12: 0000000000000000 > R13: ffff888098ab1600 R14: 0000000000000000 R15: 0000000000000000 > FS: 0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007ffd51c40664 CR3: 0000000092641000 CR4: 00000000001406f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > io_sq_thread+0x1c7/0xa20 fs/io_uring.c:3274 > kthread+0x361/0x430 kernel/kthread.c:255 > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 > Modules linked in: > ---[ end trace f2e1a4307fbe2245 ]--- > RIP: 0010:creds_are_invalid kernel/cred.c:792 [inline] > RIP: 0010:__validate_creds include/linux/cred.h:187 [inline] > RIP: 0010:override_creds+0x9f/0x170 kernel/cred.c:550 > Code: ac 25 00 81 fb 64 65 73 43 0f 85 a3 37 00 00 e8 17 ab 25 00 49 8d 7c > 24 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 > c0 74 08 3c 03 0f 8e 96 00 00 00 41 8b 5c 24 10 bf > RSP: 0018:ffff88809c45fda0 EFLAGS: 00010202 > RAX: dffffc0000000000 RBX: 0000000043736564 RCX: ffffffff814f3318 > RDX: 0000000000000002 RSI: ffffffff814f3329 RDI: 0000000000000010 > RBP: ffff88809c45fdb8 R08: ffff8880a3aac240 R09: ffffed1014755849 > R10: ffffed1014755848 R11: ffff8880a3aac247 R12: 0000000000000000 > R13: ffff888098ab1600 R14: 0000000000000000 R15: 0000000000000000 > FS: 0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007ffd51c40664 CR3: 0000000092641000 CR4: 00000000001406f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > --- > This bug 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 bug report. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > syzbot can test patches for this bug, for details see: > https://goo.gl/tpsmEJ#testing-patches > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000da160a0598b2c704%40google.com. ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: general protection fault in override_creds 2019-12-02 6:40 ` general protection fault in override_creds Dmitry Vyukov @ 2019-12-02 15:40 ` Jens Axboe 2019-12-02 15:49 ` Jens Axboe 0 siblings, 1 reply; 4+ messages in thread From: Jens Axboe @ 2019-12-02 15:40 UTC (permalink / raw) To: Dmitry Vyukov, syzbot, Al Viro, io-uring, linux-fsdevel Cc: Anna.Schumaker, Casey Schaufler, David Howells, Jann Horn, Kees Cook, Kate Stewart, LKML, NeilBrown, syzkaller-bugs, Thomas Gleixner On 12/1/19 10:40 PM, Dmitry Vyukov wrote: > On Mon, Dec 2, 2019 at 7:35 AM syzbot > <syzbot+5320383e16029ba057ff@syzkaller.appspotmail.com> wrote: >> >> Hello, >> >> syzbot found the following crash on: >> >> HEAD commit: b94ae8ad Merge tag 'seccomp-v5.5-rc1' of git://git.kernel... >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=10f9ffcee00000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=ff560c3de405258c >> dashboard link: https://syzkaller.appspot.com/bug?extid=5320383e16029ba057ff >> compiler: gcc (GCC) 9.0.0 20181231 (experimental) >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12dd682ae00000 >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16290abce00000 >> >> IMPORTANT: if you fix the bug, please add the following tag to the commit: >> Reported-by: syzbot+5320383e16029ba057ff@syzkaller.appspotmail.com > > I think this relates to fs/io_uring.c rather than kernel/cred.c. > +io_uring maintainers Yeah that's my fault, guessing the below will fix it. I'll test and queue it up. diff --git a/fs/io_uring.c b/fs/io_uring.c index ec53aa7cdc94..afafe0463d2d 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -4361,7 +4361,8 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx) io_unaccount_mem(ctx->user, ring_pages(ctx->sq_entries, ctx->cq_entries)); free_uid(ctx->user); - put_cred(ctx->creds); + if (ctx->creds) + put_cred(ctx->creds); kfree(ctx->completions); kmem_cache_free(req_cachep, ctx->fallback_req); kfree(ctx); @@ -4759,7 +4760,12 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) ctx->compat = in_compat_syscall(); ctx->account_mem = account_mem; ctx->user = user; + ctx->creds = prepare_creds(); + if (!ctx->creds) { + ret = -ENOMEM; + goto err; + } ret = io_allocate_scq_urings(ctx, p); if (ret) -- Jens Axboe ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: general protection fault in override_creds 2019-12-02 15:40 ` Jens Axboe @ 2019-12-02 15:49 ` Jens Axboe 0 siblings, 0 replies; 4+ messages in thread From: Jens Axboe @ 2019-12-02 15:49 UTC (permalink / raw) To: Dmitry Vyukov, syzbot, Al Viro, io-uring, linux-fsdevel Cc: Anna.Schumaker, Casey Schaufler, David Howells, Jann Horn, Kees Cook, Kate Stewart, LKML, NeilBrown, syzkaller-bugs, Thomas Gleixner On 12/2/19 7:40 AM, Jens Axboe wrote: > On 12/1/19 10:40 PM, Dmitry Vyukov wrote: >> On Mon, Dec 2, 2019 at 7:35 AM syzbot >> <syzbot+5320383e16029ba057ff@syzkaller.appspotmail.com> wrote: >>> >>> Hello, >>> >>> syzbot found the following crash on: >>> >>> HEAD commit: b94ae8ad Merge tag 'seccomp-v5.5-rc1' of git://git.kernel... >>> git tree: upstream >>> console output: https://syzkaller.appspot.com/x/log.txt?x=10f9ffcee00000 >>> kernel config: https://syzkaller.appspot.com/x/.config?x=ff560c3de405258c >>> dashboard link: https://syzkaller.appspot.com/bug?extid=5320383e16029ba057ff >>> compiler: gcc (GCC) 9.0.0 20181231 (experimental) >>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12dd682ae00000 >>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16290abce00000 >>> >>> IMPORTANT: if you fix the bug, please add the following tag to the commit: >>> Reported-by: syzbot+5320383e16029ba057ff@syzkaller.appspotmail.com >> >> I think this relates to fs/io_uring.c rather than kernel/cred.c. >> +io_uring maintainers > > Yeah that's my fault, guessing the below will fix it. I'll test and > queue it up. This is cleaner, tested fine. diff --git a/fs/io-wq.c b/fs/io-wq.c index 91b85df0861e..74b40506c5d9 100644 --- a/fs/io-wq.c +++ b/fs/io-wq.c @@ -111,7 +111,7 @@ struct io_wq { struct task_struct *manager; struct user_struct *user; - struct cred *creds; + const struct cred *creds; struct mm_struct *mm; refcount_t refs; struct completion done; diff --git a/fs/io-wq.h b/fs/io-wq.h index 600e0158cba7..dd0af0d7376c 100644 --- a/fs/io-wq.h +++ b/fs/io-wq.h @@ -87,7 +87,7 @@ typedef void (put_work_fn)(struct io_wq_work *); struct io_wq_data { struct mm_struct *mm; struct user_struct *user; - struct cred *creds; + const struct cred *creds; get_work_fn *get_work; put_work_fn *put_work; diff --git a/fs/io_uring.c b/fs/io_uring.c index ec53aa7cdc94..5cab7a047317 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -238,7 +238,7 @@ struct io_ring_ctx { struct user_struct *user; - struct cred *creds; + const struct cred *creds; /* 0 is for ctx quiesce/reinit/free, 1 is for sqo_thread started */ struct completion *completions; @@ -4759,7 +4759,7 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) ctx->compat = in_compat_syscall(); ctx->account_mem = account_mem; ctx->user = user; - ctx->creds = prepare_creds(); + ctx->creds = get_current_cred(); ret = io_allocate_scq_urings(ctx, p); if (ret) -- Jens Axboe ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: general protection fault in override_creds [not found] <000000000000da160a0598b2c704@google.com> 2019-12-02 6:40 ` general protection fault in override_creds Dmitry Vyukov @ 2019-12-02 15:22 ` syzbot 1 sibling, 0 replies; 4+ messages in thread From: syzbot @ 2019-12-02 15:22 UTC (permalink / raw) To: Anna.Schumaker, Anna.Schumaker, axboe, casey, dhowells, dvyukov, io-uring, jannh, keescook, kstewart, linux-block, linux-fsdevel, linux-kernel, neilb, syzkaller-bugs, tglx, viro syzbot has bisected this bug to: commit 181e448d8709e517c9c7b523fcd209f24eb38ca7 Author: Jens Axboe <axboe@kernel.dk> Date: Mon Nov 25 15:52:30 2019 +0000 io_uring: async workers should inherit the user creds bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=10424ceae00000 start commit: b94ae8ad Merge tag 'seccomp-v5.5-rc1' of git://git.kernel... git tree: upstream final crash: https://syzkaller.appspot.com/x/report.txt?x=12424ceae00000 console output: https://syzkaller.appspot.com/x/log.txt?x=14424ceae00000 kernel config: https://syzkaller.appspot.com/x/.config?x=ff560c3de405258c dashboard link: https://syzkaller.appspot.com/bug?extid=5320383e16029ba057ff syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12dd682ae00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16290abce00000 Reported-by: syzbot+5320383e16029ba057ff@syzkaller.appspotmail.com Fixes: 181e448d8709 ("io_uring: async workers should inherit the user creds") For information about bisection process see: https://goo.gl/tpsmEJ#bisection ^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-12-02 6:40 ` general protection fault in override_creds Dmitry Vyukov
2019-12-02 15:40 ` Jens Axboe
2019-12-02 15:49 ` Jens Axboe
2019-12-02 15:22 ` syzbot
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