At Sat, 25 Dec 2010 16:23:40 -0500, Dan Rosenberg wrote:
The load_mixer_volumes() function, which can be triggered by unprivileged users via the SOUND_MIXER_SETLEVELS ioctl, is vulnerable to a buffer overflow. Because the provided "name" argument isn't guaranteed to be NULL terminated at the expected 32 bytes, it's possible to overflow past the end of the last element in the mixer_vols array. Further exploitation can result in an arbitrary kernel write (via subsequent calls to load_mixer_volumes()) leading to privilege escalation, or arbitrary kernel reads via get_mixer_levels(). In addition, the strcmp() may leak bytes beyond the mixer_vols array.
Signed-off-by: Dan Rosenberg drosenberg@vsecurity.com Cc: stable stable@kernel.org
Thanks, applied now to sound git tree. I'll send a pull request to Linus today.
Takashi
sound/oss/soundcard.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/sound/oss/soundcard.c b/sound/oss/soundcard.c index 46c0d03..fcb14a0 100644 --- a/sound/oss/soundcard.c +++ b/sound/oss/soundcard.c @@ -87,7 +87,7 @@ int *load_mixer_volumes(char *name, int *levels, int present) int i, n;
for (i = 0; i < num_mixer_volumes; i++) {
if (strcmp(name, mixer_vols[i].name) == 0) {
if (strncmp(name, mixer_vols[i].name, 32) == 0) { if (present) mixer_vols[i].num = i; return mixer_vols[i].levels;@@ -99,7 +99,7 @@ int *load_mixer_volumes(char *name, int *levels, int present) } n = num_mixer_volumes++;
- strcpy(mixer_vols[n].name, name);
strncpy(mixer_vols[n].name, name, 32);
if (present) mixer_vols[n].num = n;