CVE Published: 19/06/2024 |
CVE Updated: 05/11/2024 |
CVE Year: 2024 Source: Linux |
Vendor: Linux |
Product: Linux Status : PUBLISHED
CVE-2024-38605 Description
In the Linux kernel, the following vulnerability has been resolved:
ALSA: core: Fix NULL module pointer assignment at card init
The commit 81033c6b584b ("ALSA: core: Warn on empty module")
introduced a WARN_ON() for a NULL module pointer passed at snd_card
object creation, and it also wraps the code around it with \'#ifdef
MODULE\'. This works in most cases, but the devils are always in
details. "MODULE" is defined when the target code (i.e. the sound
core) is built as a module; but this doesn\'t mean that the caller is
also built-in or not. Namely, when only the sound core is built-in
(CONFIG_SND=y) while the driver is a module (CONFIG_SND_USB_AUDIO=m),
the passed module pointer is ignored even if it\'s non-NULL, and
card->module remains as NULL. This would result in the missing module
reference up/down at the device open/close, leading to a race with the
code execution after the module removal.
For addressing the bug, move the assignment of card->module again out
of ifdef. The WARN_ON() is still wrapped with ifdef because the
module can be really NULL when all sound drivers are built-in.
Note that we keep \'ifdef MODULE\' for WARN_ON(), otherwise it would
lead to a false-positive NULL module check. Admittedly it won\'t catch
perfectly, i.e. no check is performed when CONFIG_SND=y. But, it\'s no
real problem as it\'s only for debugging, and the condition is pretty
rare.