[PATCH rdma-rc 1/2] RDMA/core: Prevent mixed use of FDs between shared ufiles

[Leon Romanovsky <leon@kernel.org>]

From: Leon Romanovsky <leonro@mellanox.com>

FDs can only be used on the ufile that created them, they cannot be
mixed to other ufiles. We are lacking a check to prevent it.

==================================================================
BUG: KASAN: null-ptr-deref in atomic64_sub_and_test include/asm-generic/atomic-instrumented.h:1547 [inline]
BUG: KASAN: null-ptr-deref in atomic_long_sub_and_test include/asm-generic/atomic-long.h:460 [inline]
BUG: KASAN: null-ptr-deref in fput_many+0x1a/0x140 fs/file_table.c:336
Write of size 8 at addr 0000000000000038 by task syz-executor179/284

CPU: 0 PID: 284 Comm: syz-executor179 Not tainted 5.5.0-rc5+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x94/0xce lib/dump_stack.c:118
 __kasan_report+0x18f/0x1b7 mm/kasan/report.c:510
 kasan_report+0xe/0x20 mm/kasan/common.c:639
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x15d/0x1b0 mm/kasan/generic.c:192
 atomic64_sub_and_test include/asm-generic/atomic-instrumented.h:1547 [inline]
 atomic_long_sub_and_test include/asm-generic/atomic-long.h:460 [inline]
 fput_many+0x1a/0x140 fs/file_table.c:336
 rdma_lookup_put_uobject+0x85/0x130 drivers/infiniband/core/rdma_core.c:692
 uobj_put_read include/rdma/uverbs_std_types.h:96 [inline]
 _ib_uverbs_lookup_comp_file drivers/infiniband/core/uverbs_cmd.c:198 [inline]
 create_cq+0x375/0xba0 drivers/infiniband/core/uverbs_cmd.c:1006
 ib_uverbs_create_cq+0x114/0x140 drivers/infiniband/core/uverbs_cmd.c:1089
 ib_uverbs_write+0xaa5/0xdf0 drivers/infiniband/core/uverbs_main.c:769
 __vfs_write+0x7c/0x100 fs/read_write.c:494
 vfs_write+0x168/0x4a0 fs/read_write.c:558
 ksys_write+0xc8/0x200 fs/read_write.c:611
 do_syscall_64+0x9c/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x44ef99
Code: 00 b8 00 01 00 00 eb e1 e8 74 1c 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c4 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc0b74c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ffc0b74c030 RCX: 000000000044ef99
RDX: 0000000000000040 RSI: 0000000020000040 RDI: 0000000000000005
RBP: 00007ffc0b74c038 R08: 0000000000401830 R09: 0000000000401830
R10: 00007ffc0b74c038 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00000000006be018 R15: 0000000000000000
==================================================================

Fixes: cf8966b3477d ("IB/core: Add support for fd objects")
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
---
 drivers/infiniband/core/rdma_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/core/rdma_core.c b/drivers/infiniband/core/rdma_core.c
index 5128cb16bb48..8f480de5596a 100644
--- a/drivers/infiniband/core/rdma_core.c
+++ b/drivers/infiniband/core/rdma_core.c
@@ -360,7 +360,7 @@ lookup_get_fd_uobject(const struct uverbs_api_object *obj,
 	 * uverbs_uobject_fd_release(), and the caller is expected to ensure
 	 * that release is never done while a call to lookup is possible.
 	 */
-	if (f->f_op != fd_type->fops) {
+	if (f->f_op != fd_type->fops || uobject->ufile != ufile) {
 		fput(f);
 		return ERR_PTR(-EBADF);
 	}
-- 
2.25.2