From 15bb318416e1bf6b6b557006a37d1da86c3a76a8 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Sebastian=20Dr=C3=B6ge?= Date: Mon, 30 Sep 2024 21:40:44 +0300 Subject: [PATCH 1/2] ssaparse: Search for closing brace after opening brace Otherwise removing anything between the braces leads to out of bound writes if there is a closing brace before the first opening brace. Thanks to Antonio Morales for finding and reporting the issue. Fixes GHSL-2024-228 Fixes https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/3870 Part-of: --- subprojects/gst-plugins-base/gst/subparse/gstssaparse.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/subprojects/gst-plugins-base/gst/subparse/gstssaparse.c b/subprojects/gst-plugins-base/gst/subparse/gstssaparse.c index 42fbb42b99fe..37b892e92843 100644 --- a/subprojects/gst-plugins-base/gst/subparse/gstssaparse.c +++ b/subprojects/gst-plugins-base/gst/subparse/gstssaparse.c @@ -238,7 +238,7 @@ gst_ssa_parse_remove_override_codes (GstSsaParse * parse, gchar * txt) gboolean removed_any = FALSE; while ((t = strchr (txt, '{'))) { - end = strchr (txt, '}'); + end = strchr (t, '}'); if (end == NULL) { GST_WARNING_OBJECT (parse, "Missing { for style override code"); return removed_any; -- GitLab From 403b10eba06679319aa2e35d310236234782102f Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Sebastian=20Dr=C3=B6ge?= Date: Mon, 30 Sep 2024 18:36:19 +0300 Subject: [PATCH 2/2] ssaparse: Don't use strstr() on strings that are potentially not NULL-terminated Part-of: --- .../gst/subparse/gstssaparse.c | 36 ++++++++++++++++++- subprojects/gst-plugins-base/meson.build | 1 + 2 files changed, 36 insertions(+), 1 deletion(-) diff --git a/subprojects/gst-plugins-base/gst/subparse/gstssaparse.c b/subprojects/gst-plugins-base/gst/subparse/gstssaparse.c index 37b892e92843..c162a542f581 100644 --- a/subprojects/gst-plugins-base/gst/subparse/gstssaparse.c +++ b/subprojects/gst-plugins-base/gst/subparse/gstssaparse.c @@ -146,6 +146,35 @@ gst_ssa_parse_sink_event (GstPad * pad, GstObject * parent, GstEvent * event) return res; } +#ifndef HAVE_MEMMEM +// memmem() is a GNU extension so if it's not available we'll need +// our own implementation here. Thanks C. +static void * +my_memmem (const void *haystack, size_t haystacklen, const void *needle, + size_t needlelen) +{ + const guint8 *cur, *end; + + if (needlelen > haystacklen) + return NULL; + if (needlelen == 0) + return (void *) haystack; + + + cur = haystack; + end = cur + haystacklen - needlelen; + + for (; cur <= end; cur++) { + if (memcmp (cur, needle, needlelen) == 0) + return (void *) cur; + } + + return NULL; +} +#else +#define my_memmem memmem +#endif + static gboolean gst_ssa_parse_setcaps (GstPad * sinkpad, GstCaps * caps) { @@ -154,6 +183,7 @@ gst_ssa_parse_setcaps (GstPad * sinkpad, GstCaps * caps) const GValue *val; GstStructure *s; const guchar bom_utf8[] = { 0xEF, 0xBB, 0xBF }; + const guint8 header[] = "[Script Info]"; const gchar *end; GstBuffer *priv; GstMapInfo map; @@ -193,7 +223,7 @@ gst_ssa_parse_setcaps (GstPad * sinkpad, GstCaps * caps) left -= 3; } - if (!strstr (ptr, "[Script Info]")) + if (!my_memmem (ptr, left, header, sizeof (header) - 1)) goto invalid_init; if (!g_utf8_validate (ptr, left, &end)) { @@ -231,6 +261,10 @@ invalid_init: } } +#ifdef my_memmem +#undef my_memmem +#endif + static gboolean gst_ssa_parse_remove_override_codes (GstSsaParse * parse, gchar * txt) { diff --git a/subprojects/gst-plugins-base/meson.build b/subprojects/gst-plugins-base/meson.build index d1033bef4a96..65d094411424 100644 --- a/subprojects/gst-plugins-base/meson.build +++ b/subprojects/gst-plugins-base/meson.build @@ -197,6 +197,7 @@ check_functions = [ ['HAVE_LRINTF', 'lrintf', '#include'], ['HAVE_MMAP', 'mmap', '#include'], ['HAVE_LOG2', 'log2', '#include'], + ['HAVE_MEMMEM', 'memmem', '#include'], ] libm = cc.find_library('m', required : false) -- GitLab