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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-488ede1e217sm132187635e9.5.2026.04.14.14.21.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Apr 2026 14:21:41 -0700 (PDT) Date: Tue, 14 Apr 2026 22:21:40 +0100 From: David Laight To: Ian Rogers Cc: Arnaldo Carvalho de Melo , Peter Zijlstra , Ingo Molnar , Namhyung Kim , Alexander Shishkin , Jiri Olsa , Adrian Hunter , James Clark , Swapnil Sapkal , Anubhav Shelat , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1] perf header: Ensure read strings are '\0' terminated Message-ID: <20260414222140.2c9b8cee@pumpkin> In-Reply-To: <20260414205725.2211169-1-irogers@google.com> References: <20260414205725.2211169-1-irogers@google.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 14 Apr 2026 13:57:25 -0700 Ian Rogers wrote: > Sashiko reviews were complaining do_read_string didn't necessarily > ensure strings were correctly terminated. Add checking for this and if > a string isn't correctly terminated return NULL. Actually I'd be just as worried about corrupt data giving insane lengths (eg if it processes some ascii text). For that you want a better error than just 'return NULL'. David > > Signed-off-by: Ian Rogers > --- > tools/perf/util/header.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c > index f30e48eb3fc3..fa4f6d773874 100644 > --- a/tools/perf/util/header.c > +++ b/tools/perf/util/header.c > @@ -269,6 +269,9 @@ static char *do_read_string(struct feat_fd *ff) > if (do_read_u32(ff, &len)) > return NULL; > > + if (len == 0) > + return NULL; > + > buf = malloc(len); > if (!buf) > return NULL; > @@ -279,7 +282,10 @@ static char *do_read_string(struct feat_fd *ff) > * thus the actual strlen of buf > * may be less than len > */ > - return buf; > + for (int i = (int)len - 1; i >= 0; i--) { > + if (buf[i] == '\0') > + return buf; > + } > } > > free(buf);