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[71.126.255.178]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-907ba901c24sm49954856d6.21.2026.07.23.10.43.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Jul 2026 10:43:39 -0700 (PDT) Date: Thu, 23 Jul 2026 13:43:39 -0400 Message-ID: Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Mailer: pstg-pwork:20260723_1338/pstg-lib:20260722_1430/pstg-pwork:20260723_1338 From: Paul Moore To: Zhan Xusheng Cc: Eric Paris , Ricardo Robaina , Richard Guy Briggs , audit@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Zhan Xusheng Subject: Re: [PATCH v2] audit: fix potential integer overflow in audit_log_n_string() References: <20260718050922.1980425-1-zhanxusheng@xiaomi.com> In-Reply-To: <20260718050922.1980425-1-zhanxusheng@xiaomi.com> On Jul 18, 2026 Zhan Xusheng wrote: > > audit_log_n_string() computes new_len as "slen + 3" (enclosing quotes > plus the NUL terminator) and stores it into an int, while slen is a > size_t. For a sufficiently large slen the addition can overflow and/or > the result be truncated when assigned to the int new_len, so the > "new_len > avail" check can be bypassed and the subsequent > memcpy(ptr, string, slen) can write past the skb tail. > > This is the same class of bug that was fixed for the hex sibling in > commit 65dfde57d1e2 ("audit: fix potential integer overflow in > audit_log_n_hex()"); both helpers are reached through > audit_log_n_untrustedstring() with the same length source. > > Make new_len a size_t and use check_add_overflow() to catch the > overflow, mirroring the audit_log_n_hex() fix. No functional change for > the in-tree callers, which all pass bounded lengths. > > Fixes: 168b7173959f ("AUDIT: Clean up logging of untrusted strings") > Cc: stable@vger.kernel.org > Signed-off-by: Zhan Xusheng > --- > v2: > - drop the unnecessary (size_t) cast on the constant (Paul Moore) > - emit "?" instead of "\"?\"" on overflow, matching > audit_log_n_hex() (Paul Moore) > > kernel/audit.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) Merged into audit/stable-7.2 with the intent of sending this up to Linus once it has gone through some testing. Thanks! -- paul-moore.com