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From: Luigi Rizzo <lrizzo@google.com>
To: Masami Hiramatsu <mhiramat@kernel.org>,
	Naveen N Rao <naveen@kernel.org>,
	 Luigi Rizzo <rizzo.unipi@gmail.com>,
	"David S . Miller" <davem@davemloft.net>
Cc: JP Kobryn <inwardvessel@gmail.com>,
	linux-trace-kernel@vger.kernel.org,
	 linux-kernel@vger.kernel.org, Luigi Rizzo <lrizzo@google.com>
Subject: [PATCH] kprobes: Fix NULL pointer dereference in unregister_kretprobes()
Date: Wed,  5 Aug 2026 16:12:21 +0000	[thread overview]
Message-ID: <20260805161221.2428623-1-lrizzo@google.com> (raw)

In unregister_kretprobes(), rps[i]->rph can be NULL e.g. when called
after kretprobe failed registration. Under !CONFIG_KRETPROBE_ON_RETHOOK,
the unconditional access to rps[i]->rph->rp, causes a kernel panic due
to NULL pointer dereference.

Add a NULL check for rps[i]->rph before invoking rcu_assign_pointer().

Fixes: d839a656d0f3 ("kprobes: consistent rcu api usage for kretprobe holder")
Signed-off-by: Luigi Rizzo <lrizzo@google.com>
---
 kernel/kprobes.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index bfc89083daa93..5dd4786c455de 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2359,7 +2359,8 @@ void unregister_kretprobes(struct kretprobe **rps, int num)
 #ifdef CONFIG_KRETPROBE_ON_RETHOOK
 		rethook_free(rps[i]->rh);
 #else
-		rcu_assign_pointer(rps[i]->rph->rp, NULL);
+		if (rps[i]->rph)
+			rcu_assign_pointer(rps[i]->rph->rp, NULL);
 #endif
 	}
 
-- 
2.48.1.500.g5897711438-goog


             reply	other threads:[~2026-08-05 16:12 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-05 16:12 Luigi Rizzo [this message]
2026-08-05 18:40 ` [PATCH] kprobes: Fix NULL pointer dereference in unregister_kretprobes() Bradley Morgan
2026-08-05 20:25 ` JP Kobryn
2026-08-06  0:02 ` Masami Hiramatsu
2026-08-06  7:23   ` Luigi Rizzo
2026-08-06 13:41     ` Masami Hiramatsu

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