This is a note to let you know that I've just added the patch titled RDMA/core: Prevent mixed use of FDs between shared ufiles to the 5.6-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: rdma-core-prevent-mixed-use-of-fds-between-shared-uf.patch and it can be found in the queue-5.6 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 4af83ffa2faa167400e31123b46896b06faed77d Author: Leon Romanovsky <leonro@xxxxxxxxxxxx> Date: Tue Apr 21 11:29:28 2020 +0300 RDMA/core: Prevent mixed use of FDs between shared ufiles commit 0fb00941dc63990a10951146df216fc7b0e20bc2 upstream. 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") Link: https://lore.kernel.org/r/20200421082929.311931-2-leon@xxxxxxxxxx Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx> Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxxxx> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> diff --git a/drivers/infiniband/core/rdma_core.c b/drivers/infiniband/core/rdma_core.c index 5128cb16bb485..8f480de5596a2 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); }