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authorZhengchao Shao <shaozhengchao@huawei.com>2022-11-10 20:26:06 +0800
committerDominique Martinet <asmadeus@codewreck.org>2022-11-18 22:28:32 +0900
commit11c10956515b8ec44cf4f2a7b9d8bf8b9dc05ec4 (patch)
tree253d24ee21952768d5b4c860e00c9ecbe7e464b8 /net/9p
parentf0c4d9fc9cc9462659728d168387191387e903cc (diff)
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9p/fd: fix issue of list_del corruption in p9_fd_cancel()
Syz reported the following issue: kernel BUG at lib/list_debug.c:53! invalid opcode: 0000 [#1] PREEMPT SMP KASAN RIP: 0010:__list_del_entry_valid.cold+0x5c/0x72 Call Trace: <TASK> p9_fd_cancel+0xb1/0x270 p9_client_rpc+0x8ea/0xba0 p9_client_create+0x9c0/0xed0 v9fs_session_init+0x1e0/0x1620 v9fs_mount+0xba/0xb80 legacy_get_tree+0x103/0x200 vfs_get_tree+0x89/0x2d0 path_mount+0x4c0/0x1ac0 __x64_sys_mount+0x33b/0x430 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 </TASK> The process is as follows: Thread A: Thread B: p9_poll_workfn() p9_client_create() ... ... p9_conn_cancel() p9_fd_cancel() list_del() ... ... list_del() //list_del corruption There is no lock protection when deleting list in p9_conn_cancel(). After deleting list in Thread A, thread B will delete the same list again. It will cause issue of list_del corruption. Setting req->status to REQ_STATUS_ERROR under lock prevents other cleanup paths from trying to manipulate req_list. The other thread can safely check req->status because it still holds a reference to req at this point. Link: https://lkml.kernel.org/r/20221110122606.383352-1-shaozhengchao@huawei.com Fixes: 52f1c45dde91 ("9p: trans_fd/p9_conn_cancel: drop client lock earlier") Reported-by: syzbot+9b69b8d10ab4a7d88056@syzkaller.appspotmail.com Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> [Dominique: add description of the fix in commit message] Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Diffstat (limited to 'net/9p')
-rw-r--r--net/9p/trans_fd.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index 56a186768750..bd28e63d7666 100644
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -202,9 +202,11 @@ static void p9_conn_cancel(struct p9_conn *m, int err)
list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
list_move(&req->req_list, &cancel_list);
+ req->status = REQ_STATUS_ERROR;
}
list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
list_move(&req->req_list, &cancel_list);
+ req->status = REQ_STATUS_ERROR;
}
spin_unlock(&m->req_lock);