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([2a01:e0a:9b4:d000:c3c5:df83:3a33:2c51]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47fb6b0f2ddsm8683100f8f.20.2026.07.29.08.16.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 29 Jul 2026 08:16:58 -0700 (PDT) Message-ID: Date: Wed, 29 Jul 2026 17:16:55 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/4] drm/log: Fix out-of-bounds read on empty message length To: oushixiong1025@163.com Cc: Javier Martinez Canillas , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Shixiong Ou References: <20260729084520.688087-1-oushixiong1025@163.com> Content-Language: en-US, fr From: Jocelyn Falempe In-Reply-To: <20260729084520.688087-1-oushixiong1025@163.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 29/07/2026 10:45, oushixiong1025@163.com wrote: > From: Shixiong Ou > > drm_log_draw_kmsg_record() accesses s[len - 1] to strip the trailing > newline, but len is unsigned int. If len is 0, the subtraction wraps > to UINT_MAX, causing an out-of-bounds read. > > Add an early return when len is 0. Thanks, for your contribution Reviewed-by: Jocelyn Falempe > > Signed-off-by: Shixiong Ou > --- > drivers/gpu/drm/clients/drm_log.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/clients/drm_log.c b/drivers/gpu/drm/clients/drm_log.c > index e3e02c84a4cf..294b3be1a6b3 100644 > --- a/drivers/gpu/drm/clients/drm_log.c > +++ b/drivers/gpu/drm/clients/drm_log.c > @@ -162,6 +162,9 @@ static void drm_log_draw_kmsg_record(struct drm_log_scanout *scanout, > { > u32 prefix_len = 0; > > + if (!len) > + return; > + > if (len > TS_PREFIX_LEN && s[0] == '[' && s[6] == '.' && s[TS_PREFIX_LEN] == ']') > prefix_len = TS_PREFIX_LEN + 1; >