From patchwork Tue Apr 23 16:23:37 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Beau Belgrave X-Patchwork-Id: 13640361 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 6B9BD13CF83; Tue, 23 Apr 2024 16:23:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713889427; cv=none; b=KSNfte7kqObAcCkFL7t60c2KqXZJjOybRuvEyX1Y1+n5Ml79DfONCqdNen0DvoKl14GBVlNgj274sGpgNfzgibrAhxwmi2tB6jwCPrV3Pq0csDUihGLEhArtECtGNUKd1aDYy3zurqNvY7/hIYYTRvHL8oq3nFDG2IbsmQc9DdE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713889427; c=relaxed/simple; bh=fKYVuUYF5edyTftSCxz7zqctoDERM/BF//4XAvd9R4g=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=on9NWCqwRA9XrEF0mzXCGASByURT9QEnp/UvaRB4E5gmCiSfB5FT+RuFI5Yvbie1CvPhzhX6KCv0JCJVfQMMZsrfRYnBgjKpbu9a0S/Hr1FvwrmQFp876TTSRq79fq8mDGfsc7f6IR+zFCCzeuUp8d0H7a2wyObkdF5LIRztxfY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=sBFlWpa0; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="sBFlWpa0" Received: from localhost.localdomain (unknown [4.155.48.122]) by linux.microsoft.com (Postfix) with ESMTPSA id 0A92020FFC2A; Tue, 23 Apr 2024 09:23:44 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 0A92020FFC2A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1713889424; bh=771h4bXVshWzVkVXlBvpLqIM/IohUjbVJYAEkUl/tJs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sBFlWpa0ejJOLc1xqCRwBdC4HduVSIpzO98wIKIjBklTG7X4WTfvKn5dSpyn2G7qR JjuwElkEXl627fAWqnWEGgGCXEQBCo7xlTfDFP4FZrOabq5oNL0BGi+6k+ISD/hp5k V3ZjSDawaM5czwOedMuV+soTG6+bxy02KRrIbJzI= From: Beau Belgrave To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, dcook@linux.microsoft.com Subject: [PATCH v2 1/2] tracing/user_events: Fix non-spaced field matching Date: Tue, 23 Apr 2024 16:23:37 +0000 Message-Id: <20240423162338.292-2-beaub@linux.microsoft.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240423162338.292-1-beaub@linux.microsoft.com> References: <20240423162338.292-1-beaub@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 When the ABI was updated to prevent same name w/different args, it missed an important corner case when fields don't end with a space. Typically, space is used for fields to help separate them, like "u8 field1; u8 field2". If no spaces are used, like "u8 field1;u8 field2", then the parsing works for the first time. However, the match check fails on a subsequent register, leading to confusion. This is because the match check uses argv_split() and assumes that all fields will be split upon the space. When spaces are used, we get back { "u8", "field1;" }, without spaces we get back { "u8", "field1;u8" }. This causes a mismatch, and the user program gets back -EADDRINUSE. Add a method to detect this case before calling argv_split(). If found force a space after the field separator character ';'. This ensures all cases work properly for matching. With this fix, the following are all treated as matching: u8 field1;u8 field2 u8 field1; u8 field2 u8 field1;\tu8 field2 u8 field1;\nu8 field2 Fixes: ba470eebc2f6 ("tracing/user_events: Prevent same name but different args event") Signed-off-by: Beau Belgrave --- kernel/trace/trace_events_user.c | 76 +++++++++++++++++++++++++++++++- 1 file changed, 75 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index 70d428c394b6..82b191f33a28 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -1989,6 +1989,80 @@ static int user_event_set_tp_name(struct user_event *user) return 0; } +/* + * Counts how many ';' without a trailing space are in the args. + */ +static int count_semis_no_space(char *args) +{ + int count = 0; + + while ((args = strchr(args, ';'))) { + args++; + + if (!isspace(*args)) + count++; + } + + return count; +} + +/* + * Copies the arguments while ensuring all ';' have a trailing space. + */ +static char *insert_space_after_semis(char *args, int count) +{ + char *fixed, *pos; + int len; + + len = strlen(args) + count; + fixed = kmalloc(len + 1, GFP_KERNEL); + + if (!fixed) + return NULL; + + pos = fixed; + + /* Insert a space after ';' if there is no trailing space. */ + while (*args) { + *pos = *args++; + + if (*pos++ == ';' && !isspace(*args)) + *pos++ = ' '; + } + + *pos = '\0'; + + return fixed; +} + +static char **user_event_argv_split(char *args, int *argc) +{ + char **split; + char *fixed; + int count; + + /* Count how many ';' without a trailing space */ + count = count_semis_no_space(args); + + /* No fixup is required */ + if (!count) + return argv_split(GFP_KERNEL, args, argc); + + /* We must fixup 'field;field' to 'field; field' */ + fixed = insert_space_after_semis(args, count); + + if (!fixed) + return NULL; + + /* We do a normal split afterwards */ + split = argv_split(GFP_KERNEL, fixed, argc); + + /* We can free since argv_split makes a copy */ + kfree(fixed); + + return split; +} + /* * Parses the event name, arguments and flags then registers if successful. * The name buffer lifetime is owned by this method for success cases only. @@ -2012,7 +2086,7 @@ static int user_event_parse(struct user_event_group *group, char *name, return -EPERM; if (args) { - argv = argv_split(GFP_KERNEL, args, &argc); + argv = user_event_argv_split(args, &argc); if (!argv) return -ENOMEM;