| Message ID | 20221019171218.1337614-1-harshit.m.mogalapalli@oracle.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | io_uring/msg_ring: Fix NULL pointer dereference in io_msg_send_fd() | expand |
On 10/19/22 10:12 AM, Harshit Mogalapalli wrote: > Syzkaller produced the below call trace: > > BUG: KASAN: null-ptr-deref in io_msg_ring+0x3cb/0x9f0 > Write of size 8 at addr 0000000000000070 by task repro/16399 > > CPU: 0 PID: 16399 Comm: repro Not tainted 6.1.0-rc1 #28 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 > Call Trace: > <TASK> > dump_stack_lvl+0xcd/0x134 > ? io_msg_ring+0x3cb/0x9f0 > kasan_report+0xbc/0xf0 > ? io_msg_ring+0x3cb/0x9f0 > kasan_check_range+0x140/0x190 > io_msg_ring+0x3cb/0x9f0 > ? io_msg_ring_prep+0x300/0x300 > io_issue_sqe+0x698/0xca0 > io_submit_sqes+0x92f/0x1c30 > __do_sys_io_uring_enter+0xae4/0x24b0 > .... > RIP: 0033:0x7f2eaf8f8289 > RSP: 002b:00007fff40939718 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f2eaf8f8289 > RDX: 0000000000000000 RSI: 0000000000006f71 RDI: 0000000000000004 > RBP: 00007fff409397a0 R08: 0000000000000000 R09: 0000000000000039 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004006d0 > R13: 00007fff40939880 R14: 0000000000000000 R15: 0000000000000000 > </TASK> > Kernel panic - not syncing: panic_on_warn set ... > > We don't have a NULL check on file_ptr in io_msg_send_fd() function, > so when file_ptr is NUL src_file is also NULL and get_file() > dereferences a NULL pointer and leads to above crash. > > Add a NULL check to fix this issue. > > Fixes: e6130eba8a84 ("io_uring: add support for passing fixed file descriptors") > Reported-by: syzkaller <syzkaller@googlegroups.com> > Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com> > --- > I am not completely sure whether to place the NULL check on file_ptr > which i did in this case as file_ptr is NULL, or the masked src_file. > > Similar checks are present in other files, io_uring/filetable.c has NULL > check before masking and io_uring/cancel.c has NULL check after masking > with FFS_MASK. Doesn't really matter when it's done, but we should arguably have a helper for this to avoid having differences in this pattern.
On Wed, 19 Oct 2022 10:12:18 -0700, Harshit Mogalapalli wrote: > Syzkaller produced the below call trace: > > BUG: KASAN: null-ptr-deref in io_msg_ring+0x3cb/0x9f0 > Write of size 8 at addr 0000000000000070 by task repro/16399 > > CPU: 0 PID: 16399 Comm: repro Not tainted 6.1.0-rc1 #28 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 > Call Trace: > <TASK> > dump_stack_lvl+0xcd/0x134 > ? io_msg_ring+0x3cb/0x9f0 > kasan_report+0xbc/0xf0 > ? io_msg_ring+0x3cb/0x9f0 > kasan_check_range+0x140/0x190 > io_msg_ring+0x3cb/0x9f0 > ? io_msg_ring_prep+0x300/0x300 > io_issue_sqe+0x698/0xca0 > io_submit_sqes+0x92f/0x1c30 > __do_sys_io_uring_enter+0xae4/0x24b0 > .... > RIP: 0033:0x7f2eaf8f8289 > RSP: 002b:00007fff40939718 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f2eaf8f8289 > RDX: 0000000000000000 RSI: 0000000000006f71 RDI: 0000000000000004 > RBP: 00007fff409397a0 R08: 0000000000000000 R09: 0000000000000039 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004006d0 > R13: 00007fff40939880 R14: 0000000000000000 R15: 0000000000000000 > </TASK> > Kernel panic - not syncing: panic_on_warn set ... > > [...] Applied, thanks! [1/1] io_uring/msg_ring: Fix NULL pointer dereference in io_msg_send_fd() (no commit info) Best regards,
diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c index 4a7e5d030c78..90d2fc6fd80e 100644 --- a/io_uring/msg_ring.c +++ b/io_uring/msg_ring.c @@ -95,6 +95,9 @@ static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags) msg->src_fd = array_index_nospec(msg->src_fd, ctx->nr_user_files); file_ptr = io_fixed_file_slot(&ctx->file_table, msg->src_fd)->file_ptr; + if (!file_ptr) + goto out_unlock; + src_file = (struct file *) (file_ptr & FFS_MASK); get_file(src_file);
Syzkaller produced the below call trace: BUG: KASAN: null-ptr-deref in io_msg_ring+0x3cb/0x9f0 Write of size 8 at addr 0000000000000070 by task repro/16399 CPU: 0 PID: 16399 Comm: repro Not tainted 6.1.0-rc1 #28 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 Call Trace: <TASK> dump_stack_lvl+0xcd/0x134 ? io_msg_ring+0x3cb/0x9f0 kasan_report+0xbc/0xf0 ? io_msg_ring+0x3cb/0x9f0 kasan_check_range+0x140/0x190 io_msg_ring+0x3cb/0x9f0 ? io_msg_ring_prep+0x300/0x300 io_issue_sqe+0x698/0xca0 io_submit_sqes+0x92f/0x1c30 __do_sys_io_uring_enter+0xae4/0x24b0 .... RIP: 0033:0x7f2eaf8f8289 RSP: 002b:00007fff40939718 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f2eaf8f8289 RDX: 0000000000000000 RSI: 0000000000006f71 RDI: 0000000000000004 RBP: 00007fff409397a0 R08: 0000000000000000 R09: 0000000000000039 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004006d0 R13: 00007fff40939880 R14: 0000000000000000 R15: 0000000000000000 </TASK> Kernel panic - not syncing: panic_on_warn set ... We don't have a NULL check on file_ptr in io_msg_send_fd() function, so when file_ptr is NUL src_file is also NULL and get_file() dereferences a NULL pointer and leads to above crash. Add a NULL check to fix this issue. Fixes: e6130eba8a84 ("io_uring: add support for passing fixed file descriptors") Reported-by: syzkaller <syzkaller@googlegroups.com> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com> --- I am not completely sure whether to place the NULL check on file_ptr which i did in this case as file_ptr is NULL, or the masked src_file. Similar checks are present in other files, io_uring/filetable.c has NULL check before masking and io_uring/cancel.c has NULL check after masking with FFS_MASK. --- io_uring/msg_ring.c | 3 +++ 1 file changed, 3 insertions(+)