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ALSA: core: Fix NULL module pointer assignment at card init
stable inclusion from stable-v5.10.219 commit d7ff29a429b56f04783152ad7bbd7233b740e434 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IA6S5L CVE: CVE-2024-38605 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d7ff29a429b56f04783152ad7bbd7233b740e434 -------------------------------- commit 39381fe7394e5eafac76e7e9367e7351138a29c1 upstream. The commit 81033c6b ("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. Fixes: 81033c6b ("ALSA: core: Warn on empty module") Reported-by:Xu Yang <xu.yang_2@nxp.com> Closes: https://lore.kernel.org/r/20240520170349.2417900-1-xu.yang_2@nxp.com Cc: <stable@vger.kernel.org> Signed-off-by: