From 203d86c28cd29846ff66e2d9178f870063d8de83 Mon Sep 17 00:00:00 2001 From: Dan Rosenberg Date: Sat, 25 Dec 2010 16:23:40 -0500 Subject: [PATCH] sound: Prevent buffer overflow in OSS load_mixer_volumes commit d81a12bc29ae4038770e05dce4ab7f26fd5880fb upstream. 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 Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/oss/soundcard.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/sound/oss/soundcard.c b/sound/oss/soundcard.c index 07f803e6d203..3f420ff273f8 100644 --- a/sound/oss/soundcard.c +++ b/sound/oss/soundcard.c @@ -86,7 +86,7 @@ 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; @@ -98,7 +98,7 @@ 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; -- 2.34.1