From nobody Sun Dec 14 19:28:16 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 512C8226CFC; Fri, 18 Apr 2025 18:33:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745001227; cv=none; b=QwR5KN/abgqQpnxdFjEhAVuUgWPk8lTJWiK5LlC7Nxy/ZF2pLTrH6h2I475VNQUUd9Vlth1r8X8+S3DmBEg77kGBxc4blvm5tTfnDy7O9HTEZnueWr9m/zzZdzpXZdjaRVNH8u9h7VRrWAvb/DwO7+sDhMfeajzd2J6CU1spiQ4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745001227; c=relaxed/simple; bh=mAHbmri/ydJCCCNyZ8TtbhRs/REQDtNLw4Sz7n+2K7k=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=Ju3kEU0UkIHv9mcx3leeUdcltyiceYPdPkjrRQW1rIBSWS0F4D/zGSRjiG55Ga55ob2FypQBPu5wqleJXnY9xilfXixAYpzYI3L08WXoWv7/m4hnrc9IOV+NBV4jwL5Yray0TKyJTGarpNTAFpKxzWKmKEoyEzOKQps/GvLQKmI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 11BFCC4CEEF; Fri, 18 Apr 2025 18:33:47 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.98) (envelope-from ) id 1u5qYj-0000000Db9e-0agq; Fri, 18 Apr 2025 14:35:29 -0400 Message-ID: <20250418183528.990167813@goodmis.org> User-Agent: quilt/0.68 Date: Fri, 18 Apr 2025 14:34:52 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , stable@vger.kernel.org, Andrii Nakryiko , Mykyta Yatsenko Subject: [for-linus][PATCH 6/7] tracing: Fix filter string testing References: <20250418183446.383784216@goodmis.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Steven Rostedt The filter string testing uses strncpy_from_kernel/user_nofault() to retrieve the string to test the filter against. The if() statement was incorrect as it considered 0 as a fault, when it is only negative that it faulted. Running the following commands: # cd /sys/kernel/tracing # echo "filename.ustring ~ \"/proc*\"" > events/syscalls/sys_enter_openat= /filter # echo 1 > events/syscalls/sys_enter_openat/enable # ls /proc/$$/maps # cat trace Would produce nothing, but with the fix it will produce something like: ls-1192 [007] ..... 8169.828333: sys_openat(dfd: ffffffffffffff9c= , filename: 7efc18359904, flags: 80000, mode: 0) Link: https://lore.kernel.org/all/CAEf4BzbVPQ=3DBjWztmEwBPRKHUwNfKBkS3kce-R= zka6zvbQeVpg@mail.gmail.com/ Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Andrew Morton Link: https://lore.kernel.org/20250417183003.505835fb@gandalf.local.home Fixes: 77360f9bbc7e5 ("tracing: Add test for user space strings when filter= ing on string pointers") Reported-by: Andrii Nakryiko Reported-by: Mykyta Yatsenko Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_filter.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events= _filter.c index 0993dfc1c5c1..2048560264bb 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -808,7 +808,7 @@ static __always_inline char *test_string(char *str) kstr =3D ubuf->buffer; =20 /* For safety, do not trust the string pointer */ - if (!strncpy_from_kernel_nofault(kstr, str, USTRING_BUF_SIZE)) + if (strncpy_from_kernel_nofault(kstr, str, USTRING_BUF_SIZE) < 0) return NULL; return kstr; } @@ -827,7 +827,7 @@ static __always_inline char *test_ustring(char *str) =20 /* user space address? */ ustr =3D (char __user *)str; - if (!strncpy_from_user_nofault(kstr, ustr, USTRING_BUF_SIZE)) + if (strncpy_from_user_nofault(kstr, ustr, USTRING_BUF_SIZE) < 0) return NULL; =20 return kstr; --=20 2.47.2