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[71.206.142.238]) by smtp.gmail.com with ESMTPSA id es2-20020a056214192200b00621268e14efsm4800485qvb.55.2023.06.27.11.06.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Jun 2023 11:06:04 -0700 (PDT) To: libc-alpha@sourceware.org Cc: Joe Simmons-Talbott Subject: [PATCH] vfscanf-internal: Get rid of unbounded allocas Date: Tue, 27 Jun 2023 14:05:56 -0400 Message-Id: <20230627180556.728512-1-josimmon@redhat.com> X-Mailer: git-send-email 2.40.1 MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-12.5 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H5, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Joe Simmons-Talbott via Libc-alpha From: Joe Simmons-Talbott Reply-To: Joe Simmons-Talbott Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" Replace two unbounded allocas with scratch_buffers to avoid potential stack overflow. --- stdio-common/vfscanf-internal.c | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) diff --git a/stdio-common/vfscanf-internal.c b/stdio-common/vfscanf-internal.c index bfb9baa21a..60376ccff9 100644 --- a/stdio-common/vfscanf-internal.c +++ b/stdio-common/vfscanf-internal.c @@ -335,6 +335,12 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, struct char_buffer charbuf; scratch_buffer_init (&charbuf.scratch); + struct scratch_buffer wc_ext_sbuf; + scratch_buffer_init (&wc_ext_sbuf); + + struct scratch_buffer mb_ext_sbuf; + scratch_buffer_init (&mb_ext_sbuf); + #ifdef __va_copy __va_copy (arg, argptr); #else @@ -1488,8 +1494,14 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, wcdigits[n] = (const wchar_t *) _NL_CURRENT (LC_CTYPE, _NL_CTYPE_INDIGITS0_WC + n); - wchar_t *wc_extended = (wchar_t *) - alloca ((to_level + 2) * sizeof (wchar_t)); + wchar_t *wc_extended; + if (!scratch_buffer_set_array_size + (&wc_ext_sbuf, sizeof (wchar_t), to_level + 2)) + { + done = EOF; + goto errout; + } + wc_extended = wc_ext_sbuf.data; __wmemcpy (wc_extended, wcdigits[n], to_level); wc_extended[to_level] = __towctrans (L'0' + n, map); wc_extended[to_level + 1] = '\0'; @@ -1525,7 +1537,13 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, /* Allocate memory for extended multibyte digit. */ char *mb_extended; - mb_extended = (char *) alloca (mbdigits_len + mblen + 1); + if (!scratch_buffer_set_array_size + (&mb_ext_sbuf, 1, mbdigits_len + mblen + 1)) + { + done = EOF; + goto errout; + } + mb_extended = mb_ext_sbuf.data; /* And get the mbdigits + extra_digit string. */ *(char *) __mempcpy (__mempcpy (mb_extended, mbdigits[n], @@ -3063,5 +3081,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, free (*strptr); *strptr = NULL; } + scratch_buffer_free (&wc_ext_sbuf); + scratch_buffer_free (&mb_ext_sbuf); return done; }