title: iommufd: Fix protection fault in iommufd_test_syz_conv_iova
description: In the Linux kernel, the following vulnerability has been resolved:
iommufd: Fix protection fault in iommufd_test_syz_conv_iova
Syzkaller reported the following bug:
general protection fault, probably for non-canonical address 0xdffffc0000000038: 0000 [#1] SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000001c0-0x00000000000001c7]
Call Trace:
lock_acquire
lock_acquire+0x1ce/0x4f0
down_read+0x93/0x4a0
iommufd_test_syz_conv_iova+0x56/0x1f0
iommufd_test_access_rw.isra.0+0x2ec/0x390
iommufd_test+0x1058/0x1e30
iommufd_fops_ioctl+0x381/0x510
vfs_ioctl
__do_sys_ioctl
__se_sys_ioctl
__x64_sys_ioctl+0x170/0x1e0
do_syscall_x64
do_syscall_64+0x71/0x140
This is because the new iommufd_access_change_ioas() sets access->ioas to
NULL during its process, so the lock might be gone in a concurrent racing
context.
Fix this by doing the same access->ioas sanity as iommufd_access_rw() and
iommufd_access_pin_pages() functions do.
affected:
{
product: Linux
vendor: Linux
defaultStatus: unaffected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions:
version: 9227da7816dd, lessThan: fc719ecbca45, status: affected, versionType: git
version: 9227da7816dd, lessThan: cf7c2789822d, status: affected, versionType: git
}
{
product: Linux
vendor: Linux
defaultStatus: affected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions:
version: 6.6, status: affected
version: 0, lessThan: 6.6, status: unaffected, versionType: custom
version: 6.7.9, lessThanOrEqual: 6.7.*, status: unaffected, versionType: custom
version: 6.8, lessThanOrEqual: *, status: unaffected, versionType: original_commit_for_fix
}
