Messages in this thread Patch in this message | | | Date | Wed, 6 Jul 2022 10:50:40 -0400 | From | Steven Rostedt <> | Subject | [PATCH] net: sock: tracing: Fix sock_exceed_buf_limit not to dereference stale pointer |
| |
From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
The trace event sock_exceed_buf_limit saves the prot->sysctl_mem pointer and then dereferences it in the TP_printk() portion. This is unsafe as the TP_printk() portion is executed at the time the buffer is read. That is, it can be seconds, minutes, days, months, even years later. If the proto is freed, then this dereference will can also lead to a kernel crash.
Instead, save the sysctl_mem array into the ring buffer and have the TP_printk() reference that instead. This is the proper and safe way to read pointers in trace events.
Link: https://lore.kernel.org/all/20220706052130.16368-12-kuniyu@amazon.com/
Cc: stable@vger.kernel.org Fixes: 3847ce32aea9f ("core: add tracepoints for queueing skb to rcvbuf") Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> --- include/trace/events/sock.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/include/trace/events/sock.h b/include/trace/events/sock.h index 12c315782766..777ee6cbe933 100644 --- a/include/trace/events/sock.h +++ b/include/trace/events/sock.h @@ -98,7 +98,7 @@ TRACE_EVENT(sock_exceed_buf_limit, TP_STRUCT__entry( __array(char, name, 32) - __field(long *, sysctl_mem) + __array(long, sysctl_mem, 3) __field(long, allocated) __field(int, sysctl_rmem) __field(int, rmem_alloc) @@ -110,7 +110,9 @@ TRACE_EVENT(sock_exceed_buf_limit, TP_fast_assign( strncpy(__entry->name, prot->name, 32); - __entry->sysctl_mem = prot->sysctl_mem; + __entry->sysctl_mem[0] = READ_ONCE(prot->sysctl_mem[0]); + __entry->sysctl_mem[1] = READ_ONCE(prot->sysctl_mem[1]); + __entry->sysctl_mem[2] = READ_ONCE(prot->sysctl_mem[2]); __entry->allocated = allocated; __entry->sysctl_rmem = sk_get_rmem0(sk, prot); __entry->rmem_alloc = atomic_read(&sk->sk_rmem_alloc); -- 2.35.1
| |