CVE-2024-26785

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> iommufd: Fix protection fault in iommufd_test_syz_conv_iova<br /> <br /> Syzkaller reported the following bug:<br /> <br /> general protection fault, probably for non-canonical address 0xdffffc0000000038: 0000 [#1] SMP KASAN<br /> KASAN: null-ptr-deref in range [0x00000000000001c0-0x00000000000001c7]<br /> Call Trace:<br /> lock_acquire<br /> lock_acquire+0x1ce/0x4f0<br /> down_read+0x93/0x4a0<br /> iommufd_test_syz_conv_iova+0x56/0x1f0<br /> iommufd_test_access_rw.isra.0+0x2ec/0x390<br /> iommufd_test+0x1058/0x1e30<br /> iommufd_fops_ioctl+0x381/0x510<br /> vfs_ioctl<br /> __do_sys_ioctl<br /> __se_sys_ioctl<br /> __x64_sys_ioctl+0x170/0x1e0<br /> do_syscall_x64<br /> do_syscall_64+0x71/0x140<br /> <br /> This is because the new iommufd_access_change_ioas() sets access-&gt;ioas to<br /> NULL during its process, so the lock might be gone in a concurrent racing<br /> context.<br /> <br /> Fix this by doing the same access-&gt;ioas sanity as iommufd_access_rw() and<br /> iommufd_access_pin_pages() functions do.