Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

drm/imagination: fix error checking of pvr_vm_context_lookup()

Since pvr_vm_context_lookup() returns either NULL or a pointer, then stop using IS_ERR() for checking the return value.

Using IS_ERR() leads to the kernel oops reported below. It can be reproduced by passing an invalid VM context handle from userspace to the DRM_IOCTL_PVR_CREATE_CONTEXT ioctl.

[ 92.733119] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000148 [ 92.742042] Mem abort info: [ 92.744890] ESR = 0x0000000096000004 [ 92.748686] EC = 0x25: DABT (current EL), IL = 32 bits [ 92.754020] SET = 0, FnV = 0 [ 92.757154] EA = 0, S1PTW = 0 [ 92.760337] FSC = 0x04: level 0 translation fault [ 92.765243] Data abort info: [ 92.768129] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 [ 92.773626] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 [ 92.778763] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [ 92.784098] user pgtable: 4k pages, 48-bit VAs, pgdp=000000088ed23000 [ 92.790550] [0000000000000148] pgd=0000000000000000, p4d=0000000000000000 [ 92.797381] Internal error: Oops: 0000000096000004 [#1] SMP [ 92.803027] Modules linked in: powervr [ 92.852533] CPU: 0 UID: 0 PID: 409 Comm: triangle Not tainted 7.1.0-rc5-g98b46e693b91 #1 PREEMPT [ 92.861385] Hardware name: Texas Instruments AM68 SK (DT) [ 92.866766] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 9…