| From 85dc9e7adf9b4b2a99a798e59ae2f1145cb93a37 Mon Sep 17 00:00:00 2001 |
| From: Jens Axboe <axboe@kernel.dk> |
| Date: Mon, 2 Dec 2019 08:50:00 -0700 |
| Subject: [PATCH] io_uring: use current task creds instead of allocating a new |
| one |
| |
| commit 0b8c0ec7eedcd8f9f1a1f238d87f9b512b09e71a upstream. |
| |
| syzbot reports: |
| |
| 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 |
| |
| which is caused by slab fault injection triggering a failure in |
| prepare_creds(). We don't actually need to create a copy of the creds |
| as we're not modifying it, we just need a reference on the current task |
| creds. This avoids the failure case as well, and propagates the const |
| throughout the stack. |
| |
| Fixes: 181e448d8709 ("io_uring: async workers should inherit the user creds") |
| Reported-by: syzbot+5320383e16029ba057ff@syzkaller.appspotmail.com |
| Signed-off-by: Jens Axboe <axboe@kernel.dk> |
| [PG: drop chunks not in v5.2 as per v5.3.11-stable b'port of 181e448d8709] |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/fs/io_uring.c b/fs/io_uring.c |
| index d56a78fba43d..50e9cde0288a 100644 |
| --- a/fs/io_uring.c |
| +++ b/fs/io_uring.c |
| @@ -258,7 +258,7 @@ struct io_ring_ctx { |
| |
| struct user_struct *user; |
| |
| - struct cred *creds; |
| + const struct cred *creds; |
| |
| struct completion ctx_done; |
| |
| @@ -3190,7 +3190,7 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) |
| ctx->account_mem = account_mem; |
| ctx->user = user; |
| |
| - ctx->creds = prepare_creds(); |
| + ctx->creds = get_current_cred(); |
| if (!ctx->creds) { |
| ret = -ENOMEM; |
| goto err; |
| -- |
| 2.7.4 |
| |
