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ALSA: usb-audio: Fix a stack buffer overflow bug in check_input_term 

(CVE-2019-15118)
This commit is contained in:
Romain Perier 2019-08-28 13:37:05 +02:00
parent 80e547b069
commit 484d0b5f4b
3 changed files with 137 additions and 0 deletions
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2
debian/changelog vendored
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@ -2,6 +2,8 @@ linux (4.19.67-3) UNRELEASED; urgency=medium
[ Romain Perier ]
* ALSA: usb-audio: Fix an OOB bug in parse_audio_mixer_unit (CVE-2019-15117)
* ALSA: usb-audio: Fix a stack buffer overflow bug in check_input_term
(CVE-2019-15118)
-- Romain Perier <romain.perier@gmail.com> Wed, 28 Aug 2019 13:28:09 +0200

134
debian/patches/bugfix/all/ALSA-usb-audio-Fix-a-stack-buffer-overflow-bug-in-check_input_term.patch vendored Normal file
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@ -0,0 +1,134 @@
From: Hui Peng <benquike@gmail.com>
Date: Thu, 15 Aug 2019 00:31:34 -0400
Subject: ALSA: usb-audio: Fix a stack buffer overflow bug in check_input_term
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2019-15118
Origin: https://git.kernel.org/linus/19bce474c45be69a284ecee660aa12d8f1e88f18
commit 19bce474c45be69a284ecee660aa12d8f1e88f18 upstream.
`check_input_term` recursively calls itself with input from
device side (e.g., uac_input_terminal_descriptor.bCSourceID)
as argument (id). In `check_input_term`, if `check_input_term`
is called with the same `id` argument as the caller, it triggers
endless recursive call, resulting kernel space stack overflow.
This patch fixes the bug by adding a bitmap to `struct mixer_build`
to keep track of the checked ids and stop the execution if some id
has been checked (similar to how parse_audio_unit handles unitid
argument).
Reported-by: Hui Peng <benquike@gmail.com>
Reported-by: Mathias Payer <mathias.payer@nebelwelt.net>
Signed-off-by: Hui Peng <benquike@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
sound/usb/mixer.c | 35 +++++++++++++++++++++++++++--------
1 file changed, 27 insertions(+), 8 deletions(-)
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 7e1c6c2dc99e..996126a28072 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -83,6 +83,7 @@ struct mixer_build {
unsigned char *buffer;
unsigned int buflen;
DECLARE_BITMAP(unitbitmap, MAX_ID_ELEMS);
+ DECLARE_BITMAP(termbitmap, MAX_ID_ELEMS);
struct usb_audio_term oterm;
const struct usbmix_name_map *map;
const struct usbmix_selector_map *selector_map;
@@ -788,16 +789,25 @@ static int uac_mixer_unit_get_channels(struct mixer_build *state,
* parse the source unit recursively until it reaches to a terminal
* or a branched unit.
*/
-static int check_input_term(struct mixer_build *state, int id,
+static int __check_input_term(struct mixer_build *state, int id,
struct usb_audio_term *term)
{
int protocol = state->mixer->protocol;
int err;
void *p1;
+ unsigned char *hdr;
memset(term, 0, sizeof(*term));
- while ((p1 = find_audio_control_unit(state, id)) != NULL) {
- unsigned char *hdr = p1;
+ for (;;) {
+ /* a loop in the terminal chain? */
+ if (test_and_set_bit(id, state->termbitmap))
+ return -EINVAL;
+
+ p1 = find_audio_control_unit(state, id);
+ if (!p1)
+ break;
+
+ hdr = p1;
term->id = id;
if (protocol == UAC_VERSION_1 || protocol == UAC_VERSION_2) {
@@ -815,7 +825,7 @@ static int check_input_term(struct mixer_build *state, int id,
/* call recursively to verify that the
* referenced clock entity is valid */
- err = check_input_term(state, d->bCSourceID, term);
+ err = __check_input_term(state, d->bCSourceID, term);
if (err < 0)
return err;
@@ -849,7 +859,7 @@ static int check_input_term(struct mixer_build *state, int id,
case UAC2_CLOCK_SELECTOR: {
struct uac_selector_unit_descriptor *d = p1;
/* call recursively to retrieve the channel info */
- err = check_input_term(state, d->baSourceID[0], term);
+ err = __check_input_term(state, d->baSourceID[0], term);
if (err < 0)
return err;
term->type = UAC3_SELECTOR_UNIT << 16; /* virtual type */
@@ -912,7 +922,7 @@ static int check_input_term(struct mixer_build *state, int id,
/* call recursively to verify that the
* referenced clock entity is valid */
- err = check_input_term(state, d->bCSourceID, term);
+ err = __check_input_term(state, d->bCSourceID, term);
if (err < 0)
return err;
@@ -963,7 +973,7 @@ static int check_input_term(struct mixer_build *state, int id,
case UAC3_CLOCK_SELECTOR: {
struct uac_selector_unit_descriptor *d = p1;
/* call recursively to retrieve the channel info */
- err = check_input_term(state, d->baSourceID[0], term);
+ err = __check_input_term(state, d->baSourceID[0], term);
if (err < 0)
return err;
term->type = UAC3_SELECTOR_UNIT << 16; /* virtual type */
@@ -979,7 +989,7 @@ static int check_input_term(struct mixer_build *state, int id,
return -EINVAL;
/* call recursively to retrieve the channel info */
- err = check_input_term(state, d->baSourceID[0], term);
+ err = __check_input_term(state, d->baSourceID[0], term);
if (err < 0)
return err;
@@ -997,6 +1007,15 @@ static int check_input_term(struct mixer_build *state, int id,
return -ENODEV;
}
+
+static int check_input_term(struct mixer_build *state, int id,
+ struct usb_audio_term *term)
+{
+ memset(term, 0, sizeof(*term));
+ memset(state->termbitmap, 0, sizeof(state->termbitmap));
+ return __check_input_term(state, id, term);
+}
+
/*
* Feature Unit
*/
--
cgit 1.2-0.3.lf.el7

1
debian/patches/series vendored
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@ -163,6 +163,7 @@ debian/i386-686-pae-pci-set-pci-nobios-by-default.patch
debian/ntfs-mark-it-as-broken.patch
bugfix/all/netfilter-conntrack-use-consistent-ct-id-hash-calcul.patch
bugfix/all/ALSA-usb-audio-Fix-an-OOB-bug-in-parse_audio_mixer_unit.patch
bugfix/all/ALSA-usb-audio-Fix-a-stack-buffer-overflow-bug-in-check_input_term.patch
# Fix exported symbol versions
bugfix/all/module-disable-matching-missing-version-crc.patch