CVE-2022-50240

01/Description

In the Linux kernel, the following vulnerability has been resolved: android: binder: stop saving a pointer to the VMA Do not record a pointer to a VMA outside of the mmap_lock for later use. This is unsafe and there are a number of failure paths *after* the recorded VMA pointer may be freed during setup. There is no callback to the driver to clear the saved pointer from generic mm code. Furthermore, the VMA pointer may become stale if any number of VMA operations end up freeing the VMA so saving it was fragile to being with. Instead, change the binder_alloc struct to record the start address of the VMA and use vma_lookup() to get the vma when needed. Add lockdep mmap_lock checks on updates to the vma pointer to ensure the lock is held and depend on that lock for synchronization of readers and writers - which was already the case anyways, so the smp_wmb()/smp_rmb() was not necessary. [[email protected]: fix drivers/android/binder_alloc_selftest.c]

02/Affected products

linux: linux kernel

03/References6

• git.kernel.org/stable/c/015ac18be7de25d17d6e5f1643cb3b60bfbe859e Patch
• git.kernel.org/stable/c/1ec3f76a436d750fd5023caec5da0494fc2870d2 Patch
• git.kernel.org/stable/c/27a594bc7a7c8238d239e3cdbcf2edfa3bbe9a1b Patch
• git.kernel.org/stable/c/622ef885a89ad04cfb76ee478fb44f051125d1f1 Patch
• git.kernel.org/stable/c/925e6b6f82c9c80ab3c17acbde8d16f349da7d26 Patch
• git.kernel.org/stable/c/a43cfc87caaf46710c8027a8c23b8a55f1078f19 Patch