community/mpv: add mitigation for CVE-2021-30145

2 files changed, 96 insertions, 3 deletions

diff --git a/community/mpv/APKBUILD b/community/mpv/APKBUILD
index 1b6aa051f20..a2fe91b7808 100644
--- a/community/mpv/APKBUILD
+++ b/community/mpv/APKBUILD
@@ -5,7 +5,7 @@
 # Maintainer: Natanael Copa <ncopa@alpinelinux.org>
 pkgname=mpv
 pkgver=0.33.0
-pkgrel=0
+pkgrel=1
 pkgdesc="Video player based on MPlayer/mplayer2"
 url="https://mpv.io/"
 arch="all"
@@ -60,9 +60,12 @@ subpackages="
 	$pkgname-zsh-completion:zshcomp:noarch
 	"
 options="net" # downloads a waf tarball
-source="mpv-$pkgver.tar.gz::https://github.com/mpv-player/mpv/archive/v$pkgver.tar.gz"
+source="mpv-$pkgver.tar.gz::https://github.com/mpv-player/mpv/archive/v$pkgver.tar.gz
+	CVE-2021-30145.patch"
 
 # secfixes:
+#   0.33.0-r1:
+#     - CVE-2021-30145
 #   0.27.0-r3:
 #     - CVE-2018-6360
 
@@ -122,4 +125,7 @@ zshcomp() {
 	amove usr/share/zsh/site-functions
 }
 
-sha512sums="5a4af74ba2c9656c6b61adcf944c734923c7b4527a49cd79ec63a0617911629438a138d887dfbd4b6c0c9c53e2c68c18839d98d9765179e52cc5675d0682e077  mpv-0.33.0.tar.gz"
+sha512sums="
+5a4af74ba2c9656c6b61adcf944c734923c7b4527a49cd79ec63a0617911629438a138d887dfbd4b6c0c9c53e2c68c18839d98d9765179e52cc5675d0682e077  mpv-0.33.0.tar.gz
+53033657588e8e13e8b1191440fcecc2f45dc3e41f4182d00243c8c012774e2f78bff17d2025467f7f516bda745cfdc6ead5d71e329743e17ae6c7cdddfcbc77  CVE-2021-30145.patch
+"
diff --git a/community/mpv/CVE-2021-30145.patch b/community/mpv/CVE-2021-30145.patch
new file mode 100644
index 00000000000..b02036042ca
--- /dev/null
+++ b/community/mpv/CVE-2021-30145.patch
@@ -0,0 +1,87 @@
+From d0c530919d8cd4d7a774e38ab064e0fabdae34e6 Mon Sep 17 00:00:00 2001
+From: "Avi Halachmi (:avih)" <avihpit@yahoo.com>
+Date: Sun, 4 Apr 2021 14:11:15 +0300
+Subject: [PATCH] demux_mf: improve format string processing
+
+Before this commit, the user could specify a printf format string
+which wasn't verified, and could result in:
+- Undefined behavior due to missing or non-matching arguments.
+- Buffer overflow due to untested result length.
+
+The offending code was added at commit 103a9609 (2002, mplayer svn):
+git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@4566 b3059339-0415-0410-9bf9-f77b7e298cf2
+
+It moved around but was not modified meaningfully until now.
+
+Now we reject all conversion specifiers at the format except %%
+and a simple subset of the valid specifiers. Also, we now use
+snprintf to avoid buffer overflow.
+
+The format string is provided by the user as part of mf:// URI.
+
+Report and initial patch by Stefan Schiller.
+Patch reviewed by @jeeb, @sfan5, Stefan Schiller.
+---
+ demux/demux_mf.c | 39 +++++++++++++++++++++++++++++++++++++--
+ 1 file changed, 37 insertions(+), 2 deletions(-)
+
+diff --git a/demux/demux_mf.c b/demux/demux_mf.c
+index 424821b965f..40f94f4e4ed 100644
+--- a/demux/demux_mf.c
++++ b/demux/demux_mf.c
+@@ -121,7 +121,8 @@ static mf_t *open_mf_pattern(void *talloc_ctx, struct demuxer *d, char *filename
+         goto exit_mf;
+     }
+ 
+-    char *fname = talloc_size(mf, strlen(filename) + 32);
++    size_t fname_avail = strlen(filename) + 32;
++    char *fname = talloc_size(mf, fname_avail);
+ 
+ #if HAVE_GLOB
+     if (!strchr(filename, '%')) {
+@@ -148,10 +149,44 @@ static mf_t *open_mf_pattern(void *talloc_ctx, struct demuxer *d, char *filename
+     }
+ #endif
+ 
++    // We're using arbitrary user input as printf format with 1 int argument.
++    // Any format which uses exactly 1 int argument would be valid, but for
++    // simplicity we reject all conversion specifiers except %% and simple
++    // integer specifier: %[.][NUM]d where NUM is 1-3 digits (%.d is valid)
++    const char *f = filename;
++    int MAXDIGS = 3, nspec = 0, bad_spec = 0, c;
++
++    while (nspec < 2 && (c = *f++)) {
++        if (c != '%')
++            continue;
++        if (*f != '%') {
++            nspec++;  // conversion specifier which isn't %%
++            if (*f == '.')
++                f++;
++            for (int ndig = 0; mp_isdigit(*f) && ndig < MAXDIGS; ndig++, f++)
++                /* no-op */;
++            if (*f != 'd') {
++                bad_spec++;  // not int, or beyond our validation capacity
++                break;
++            }
++        }
++        // *f is '%' or 'd'
++        f++;
++    }
++
++    // nspec==0 (zero specifiers) is rejected because fname wouldn't advance.
++    if (bad_spec || nspec != 1) {
++        mp_err(log, "unsupported expr format: '%s'\n", filename);
++        goto exit_mf;
++    }
++
+     mp_info(log, "search expr: %s\n", filename);
+ 
+     while (error_count < 5) {
+-        sprintf(fname, filename, count++);
++        if (snprintf(fname, fname_avail, filename, count++) >= fname_avail) {
++            mp_err(log, "format result too long: '%s'\n", filename);
++            goto exit_mf;
++        }
+         if (!mp_path_exists(fname)) {
+             error_count++;
+             mp_verbose(log, "file not found: '%s'\n", fname);