> Prior to access UCMA commands, the context should be initialized and
> connected to CM_ID with ucma_create_id(). In case user skips this
> step, he can provide non-valid ctx without CM_ID and cause to multiple
> NULL dereferences.
>
> [ 109.088108] BUG: unable to handle kernel NULL pointer dereference
> at 0000000000000020 [ 109.090315] IP: ucma_connect+0x138/0x1d0 [
> 109.092595] PGD 80000001dc02d067 P4D 80000001dc02d067 PUD 1da9ef067
> PMD 0 [ 109.095384] Oops: 0000 [#1] SMP KASAN PTI
> [ 109.097834] CPU: 0 PID: 663 Comm: uclose Tainted: G B 4.16.0-
> rc1-00062-g2975d5de6428 #45
> [ 109.100816] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
> BIOS rel-1.11.0-0-g63451fca13-prebuilt.qemu-project.org 04/01/2014 [
> 109.105943] RIP: 0010:ucma_connect+0x138/0x1d0 [ 109.108850] RSP:
> 0018:ffff8801c8567a80 EFLAGS: 00010246 [ 109.111484] RAX:
> 0000000000000000 RBX: 1ffff100390acf50 RCX: ffffffff9d7812e2 [
> 109.114496] RDX: 1ffffffff3f507a5 RSI: 0000000000000297 RDI:
> 0000000000000297 [ 109.117490] RBP: ffff8801daa15600 R08:
> 0000000000000000 R09: ffffed00390aceeb [ 109.120429] R10:
> 0000000000000001 R11: ffffed00390aceea R12: 0000000000000000 [
> 109.123318] R13: 0000000000000120 R14: ffff8801de6459c0 R15:
> 0000000000000118 [ 109.126221] FS: 00007fabb68d6700(0000)
> GS:ffff8801e5c00000(0000) knlGS:0000000000000000 [ 109.129468] CS:
> 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 109.132523] CR2:
> 0000000000000020 CR3: 00000001d45d8003 CR4: 00000000003606b0 [
> 109.135573] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000 [ 109.138716] DR3: 0000000000000000 DR6:
> 00000000fffe0ff0 DR7: 0000000000000400 [ 109.142057] Call Trace:
> [ 109.144160] ? ucma_listen+0x110/0x110 [ 109.146386] ?
> wake_up_q+0x59/0x90 [ 109.148853] ? futex_wake+0x10b/0x2a0 [
> 109.151297] ? save_stack+0x89/0xb0 [ 109.153489] ?
> _copy_from_user+0x5e/0x90 [ 109.155500] ucma_write+0x174/0x1f0 [
> 109.157933] ? ucma_resolve_route+0xf0/0xf0 [ 109.160389] ?
> __mod_node_page_state+0x1d/0x80 [ 109.162706] __vfs_write+0xc4/0x350
> [ 109.164911] ? kernel_read+0xa0/0xa0 [ 109.167121] ?
> path_openat+0x1b10/0x1b10 [ 109.169355] ? fsnotify+0x899/0x8f0 [
> 109.171567] ? fsnotify_unmount_inodes+0x170/0x170
> [ 109.174145] ? __fget+0xa8/0xf0
> [ 109.177110] vfs_write+0xf7/0x280
> [ 109.179532] SyS_write+0xa1/0x120
> [ 109.181885] ? SyS_read+0x120/0x120
> [ 109.184482] ? compat_start_thread+0x60/0x60 [ 109.187124] ?
> SyS_read+0x120/0x120 [ 109.189548] do_syscall_64+0xeb/0x250 [
> 109.192178] entry_SYSCALL_64_after_hwframe+0x21/0x86
> [ 109.194725] RIP: 0033:0x7fabb61ebe99
> [ 109.197040] RSP: 002b:00007fabb68d5e98 EFLAGS: 00000202 ORIG_RAX:
> 0000000000000001 [ 109.200294] RAX: ffffffffffffffda RBX:
> 0000000000000000 RCX: 00007fabb61ebe99 [ 109.203399] RDX:
> 0000000000000120 RSI: 00000000200001c0 RDI: 0000000000000004 [
> 109.206548] RBP: 00007fabb68d5ec0 R08: 0000000000000000 R09:
> 0000000000000000 [ 109.209902] R10: 0000000000000000 R11:
> 0000000000000202 R12: 00007fabb68d5fc0 [ 109.213327] R13:
> 0000000000000000 R14: 00007fff40ab2430 R15: 00007fabb68d69c0 [
> 109.216613] Code: 88 44 24 2c 0f b6 84 24 6e 01 00 00 88 44 24 2d 0f
> b6 84 24 69 01 00 00 88 44 24 2e 8b 44 24 60 89 44 24 30 e8 da f6 06
> ff
> 31 c0 <66> 41 83 7c 24 20 1b 75 04 8b 44 24 64 48 8d 74 24 20 4c 89 e7
> [ 109.223602] RIP: ucma_connect+0x138/0x1d0 RSP: ffff8801c8567a80 [
> 109.226256] CR2: 0000000000000020
>
> Fixes: 75216638572f ("RDMA/cma: Export rdma cm interface to
> userspace")
> Reported-by: <syzbot+36712f50b0552615bf59@xxxxxxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
> ---
> drivers/infiniband/core/ucma.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/infiniband/core/ucma.c
> b/drivers/infiniband/core/ucma.c index 3f3f7bbc4528..718ed16688a8
> 100644
> --- a/drivers/infiniband/core/ucma.c
> +++ b/drivers/infiniband/core/ucma.c
> @@ -132,7 +132,7 @@ static inline struct ucma_context
> *_ucma_find_context(int id,
> ctx = idr_find(&ctx_idr, id);
> if (!ctx)
> ctx = ERR_PTR(-ENOENT);
> - else if (ctx->file != file)
> + else if (ctx->file != file || !ctx->cm_id)
After looking at the use-after-free patch, we may want this check to be
!IS_ERR_OR_NULL(ctx->cm_id)
> ctx = ERR_PTR(-EINVAL);
> return ctx;
> }
- Sean
--
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