From: Adam Zabrocki Date: Fri, 22 Apr 2022 16:40:27 +0000 (+0200) Subject: kprobes: Fix KRETPROBES when CONFIG_KRETPROBE_ON_RETHOOK is set X-Git-Tag: baikal/aarch64/sdk6.1~4137^2~10^2~1 X-Git-Url: https://git.baikalelectronics.ru/sdk/?a=commitdiff_plain;h=82b985e208a06190d6834316dc0522c959ea18e0;p=kernel.git kprobes: Fix KRETPROBES when CONFIG_KRETPROBE_ON_RETHOOK is set The recent kernel change in 82175015cf59 ("kprobes: Use rethook for kretprobe if possible"), introduced a potential NULL pointer dereference bug in the KRETPROBE mechanism. The official Kprobes documentation defines that "Any or all handlers can be NULL". Unfortunately, there is a missing return handler verification to fulfill these requirements and can result in a NULL pointer dereference bug. This patch adds such verification in kretprobe_rethook_handler() function. Fixes: 82175015cf59 ("kprobes: Use rethook for kretprobe if possible") Signed-off-by: Adam Zabrocki Signed-off-by: Daniel Borkmann Acked-by: Masami Hiramatsu Cc: Steven Rostedt Cc: Naveen N. Rao Cc: Anil S. Keshavamurthy Link: https://lore.kernel.org/bpf/20220422164027.GA7862@pi3.com.pl --- diff --git a/kernel/kprobes.c b/kernel/kprobes.c index dbe57df2e199e..dd58c0be9ce25 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -2126,7 +2126,7 @@ static void kretprobe_rethook_handler(struct rethook_node *rh, void *data, struct kprobe_ctlblk *kcb; /* The data must NOT be null. This means rethook data structure is broken. */ - if (WARN_ON_ONCE(!data)) + if (WARN_ON_ONCE(!data) || !rp->handler) return; __this_cpu_write(current_kprobe, &rp->kp);