4.19-stable patches

added patches:
	alsa-pcm-move-rwsem-lock-inside-snd_ctl_elem_read-to-prevent-uaf.patch

diff --git a/queue-4.19/alsa-pcm-move-rwsem-lock-inside-snd_ctl_elem_read-to-prevent-uaf.patch b/queue-4.19/alsa-pcm-move-rwsem-lock-inside-snd_ctl_elem_read-to-prevent-uaf.patch
new file mode 100644 (file)
index 0000000..27d4721
--- /dev/null
+++ b/queue-4.19/alsa-pcm-move-rwsem-lock-inside-snd_ctl_elem_read-to-prevent-uaf.patch
@@ -0,0 +1,64 @@
+From 56b88b50565cd8b946a2d00b0c83927b7ebb055e Mon Sep 17 00:00:00 2001
+From: Clement Lecigne <clecigne@google.com>
+Date: Fri, 13 Jan 2023 13:07:45 +0100
+Subject: ALSA: pcm: Move rwsem lock inside snd_ctl_elem_read to prevent UAF
+
+From: Clement Lecigne <clecigne@google.com>
+
+[ Note: this is a fix that works around the bug equivalently as the
+  two upstream commits:
+   1fa4445f9adf ("ALSA: control - introduce snd_ctl_notify_one() helper")
+   56b88b50565c ("ALSA: pcm: Move rwsem lock inside snd_ctl_elem_read to prevent UAF")
+  but in a simpler way to fit with older stable trees -- tiwai ]
+
+Add missing locking in ctl_elem_read_user/ctl_elem_write_user which can be
+easily triggered and turned into an use-after-free.
+
+Example code paths with SNDRV_CTL_IOCTL_ELEM_READ:
+
+64-bits:
+snd_ctl_ioctl
+  snd_ctl_elem_read_user
+    [takes controls_rwsem]
+    snd_ctl_elem_read [lock properly held, all good]
+    [drops controls_rwsem]
+
+32-bits (compat):
+snd_ctl_ioctl_compat
+  snd_ctl_elem_write_read_compat
+    ctl_elem_write_read
+      snd_ctl_elem_read [missing lock, not good]
+
+CVE-2023-0266 was assigned for this issue.
+
+Signed-off-by: Clement Lecigne <clecigne@google.com>
+Cc: stable@kernel.org # 5.12 and older
+Signed-off-by: Takashi Iwai <tiwai@suse.de>
+Reviewed-by: Jaroslav Kysela <perex@perex.cz>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ sound/core/control_compat.c |    4 ++++
+ 1 file changed, 4 insertions(+)
+
+--- a/sound/core/control_compat.c
++++ b/sound/core/control_compat.c
+@@ -319,7 +319,9 @@ static int ctl_elem_read_user(struct snd
+       err = snd_power_wait(card, SNDRV_CTL_POWER_D0);
+       if (err < 0)
+               goto error;
++      down_read(&card->controls_rwsem);
+       err = snd_ctl_elem_read(card, data);
++      up_read(&card->controls_rwsem);
+       if (err < 0)
+               goto error;
+       err = copy_ctl_value_to_user(userdata, valuep, data, type, count);
+@@ -347,7 +349,9 @@ static int ctl_elem_write_user(struct sn
+       err = snd_power_wait(card, SNDRV_CTL_POWER_D0);
+       if (err < 0)
+               goto error;
++      down_write(&card->controls_rwsem);
+       err = snd_ctl_elem_write(card, file, data);
++      up_write(&card->controls_rwsem);
+       if (err < 0)
+               goto error;
+       err = copy_ctl_value_to_user(userdata, valuep, data, type, count);

diff --git a/queue-4.19/series b/queue-4.19/series
index f5669eff0097cfcceb5482ba6b2a8b73ffe806c4..553521d49595d36be552314225c0204be3f21839 100644 (file)
--- a/queue-4.19/series
+++ b/queue-4.19/series
@@ -464,3 +464,4 @@ parisc-align-parisc-madv_xxx-constants-with-all-other-architectures.patch
 driver-core-fix-bus_type.match-error-handling-in-__driver_attach.patch
 net-sched-disallow-noqueue-for-qdisc-classes.patch
 net-ulp-prevent-ulp-without-clone-op-from-entering-the-listen-status.patch
+alsa-pcm-move-rwsem-lock-inside-snd_ctl_elem_read-to-prevent-uaf.patch