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[87.106.108.193]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43d1e2a6f73sm11320543f8f.8.2026.04.02.13.30.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Apr 2026 13:30:38 -0700 (PDT) Date: Thu, 2 Apr 2026 22:30:36 +0200 From: =?iso-8859-1?Q?G=FCnther?= Noack To: =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= Cc: =?iso-8859-1?Q?G=FCnther?= Noack , linux-security-module@vger.kernel.org, Justin Suess , Tingmao Wang , stable@vger.kernel.org Subject: Re: [PATCH v3 1/5] selftests/landlock: Fix snprintf truncation checks in audit helpers Message-ID: <20260402.554667d35637@gnoack.org> References: <20260402192608.1458252-1-mic@digikod.net> <20260402192608.1458252-2-mic@digikod.net> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260402192608.1458252-2-mic@digikod.net> On Thu, Apr 02, 2026 at 09:26:02PM +0200, Mickaël Salaün wrote: > snprintf() returns the number of characters that would have been > written, excluding the terminating NUL byte. When the output is > truncated, this return value equals or exceeds the buffer size. Fix > matches_log_domain_allocated() and matches_log_domain_deallocated() to > detect truncation with ">=" instead of ">". > > Cc: Günther Noack > Cc: stable@vger.kernel.org > Fixes: 6a500b22971c ("selftests/landlock: Add tests for audit flags and domain IDs") > Reviewed-by: Günther Noack > Signed-off-by: Mickaël Salaün > --- > > Changes since v1: > https://lore.kernel.org/r/20260312100444.2609563-8-mic@digikod.net > - New patch (split from the drain fix). > --- > tools/testing/selftests/landlock/audit.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/landlock/audit.h b/tools/testing/selftests/landlock/audit.h > index 44eb433e9666..1049a0582af5 100644 > --- a/tools/testing/selftests/landlock/audit.h > +++ b/tools/testing/selftests/landlock/audit.h > @@ -309,7 +309,7 @@ static int __maybe_unused matches_log_domain_allocated(int audit_fd, pid_t pid, > > log_match_len = > snprintf(log_match, sizeof(log_match), log_template, pid); > - if (log_match_len > sizeof(log_match)) > + if (log_match_len >= sizeof(log_match)) > return -E2BIG; > > return audit_match_record(audit_fd, AUDIT_LANDLOCK_DOMAIN, log_match, > @@ -326,7 +326,7 @@ static int __maybe_unused matches_log_domain_deallocated( > > log_match_len = snprintf(log_match, sizeof(log_match), log_template, > num_denials); > - if (log_match_len > sizeof(log_match)) > + if (log_match_len >= sizeof(log_match)) > return -E2BIG; > > return audit_match_record(audit_fd, AUDIT_LANDLOCK_DOMAIN, log_match, > -- > 2.53.0 > Reviewed-by: Günther Noack (I noticed the Reviewed-by tag was already there, re-sending to confirm that this also applies to this subset of the original patch) –Günther