CVE-2026-68261: drm/imagination: fix error checking of pvr_vm_context_lookup()

CVE-2026-68261: drm/imagination: fix error checking of pvr_vm_context_lookup()

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

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=--)
[   92.873709] pc : pvr_vm_get_fw_mem_context+0x0/0xc [powervr]
[   92.879376] lr : pvr_queue_create+0x26c/0x440 [powervr]
[   92.884595] sp : ffff8000837fbb00
[   92.887895] x29: ffff8000837fbb60 x28: 0000000000000000 x27: ffff8000837fbce8
[   92.895015] x26: ffff000807f61a40 x25: ffff000807f61a00 x24: ffff000807f64400
[   92.902135] x23: ffff00080a5ab000 x22: ffff800079b24730 x21: ffff000807f61800
[   92.909254] x20: ffff00080999e680 x19: 0000000000000000 x18: 0000000000000000
[   92.916373] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000001
[   92.923492] x14: 0000000000000000 x13: 0000000000000002 x12: ffff80008145b298
[   92.930611] x11: ffff8000844e5000 x10: ffff80008165a130 x9 : 0000000000000100
[   92.937730] x8 : 0000000000000001 x7 : ffff0008076b27e0 x6 : ffff00080ec43b7c
[   92.944850] x5 : ffff00080ec43b78 x4 : 0000000000000000 x3 : ffff00080999e680
[   92.951968] x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
[   92.959088] Call trace:
[   92.961521]  pvr_vm_get_fw_mem_context+0x0/0xc [powervr] (P)
[   92.967173]  pvr_context_create+0x190/0x410 [powervr]
[   92.972218]  pvr_ioctl_create_context+0x44/0x8c [powervr]
[   92.977608]  drm_ioctl_kernel+0xbc/0x124 [drm]
[   92.982127]  drm_ioctl+0x1f8/0x4dc [drm]
[   92.986098]  __arm64_sys_ioctl+0xac/0x104
[   92.990102]  invoke_syscall+0x54/0x10c
[   92.993842]  el0_svc_common.constprop.0+0x40/0xe0
[   92.998532]  do_el0_svc+0x1c/0x28
[   93.001835]  el0_svc+0x38/0x11c
[   93.004969]  el0t_64_sync_handler+0xa0/0xe4
[   93.009139]  el0t_64_sync+0x198/0x19c
[   93.012792] Code: aa1703e0 d2800014 95cb0ba4 17ffffe8 (f940a400)
[   93.018869] ---[ end trace 0000000000000000 ]---

The Linux kernel CVE team has assigned CVE-2026-68261 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.8 with commit d2d79d29bb98a32c511f7339a8e93b47544fdeac and fixed in 6.12.101 with commit ce97192087c659f2e0c0c2a627330c7edcc9eeb3
	Issue introduced in 6.8 with commit d2d79d29bb98a32c511f7339a8e93b47544fdeac and fixed in 6.18.42 with commit c45fafa69fe3f79e319369cf665da89868e3ef98
	Issue introduced in 6.8 with commit d2d79d29bb98a32c511f7339a8e93b47544fdeac and fixed in 7.1.6 with commit 401fbe3b6bbb6c94c24ee8843b7beed5111491ac
	Issue introduced in 6.8 with commit d2d79d29bb98a32c511f7339a8e93b47544fdeac and fixed in 7.2-rc3 with commit cf385cf6e713eba0720651174dac0b2d2f5bb8f8

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-68261
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/gpu/drm/imagination/pvr_context.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/ce97192087c659f2e0c0c2a627330c7edcc9eeb3
	https://git.kernel.org/stable/c/c45fafa69fe3f79e319369cf665da89868e3ef98
	https://git.kernel.org/stable/c/401fbe3b6bbb6c94c24ee8843b7beed5111491ac
	https://git.kernel.org/stable/c/cf385cf6e713eba0720651174dac0b2d2f5bb8f8