[Intel-gfx] [PATCH] drm/i915/gem: missing boundary check in vm_access leads to OOB read/write

[Mastan Katragadda]

Intel ID: PSIRT-PTK0002429

A missing bounds check in vm_access() in drivers/gpu/drm/i915/gem/i915_gem_mman.c
can lead to an out-of-bounds read or write in the adjacent memory area.
The len attribute is not validated before the memcpy at  [1]or [2] occurs.

[  183.637831] BUG: unable to handle page fault for address: ffffc90000c86000
[  183.637934] #PF: supervisor read access in kernel mode
[  183.637997] #PF: error_code(0x0000) - not-present page
[  183.638059] PGD 100000067 P4D 100000067 PUD 100258067 PMD 106341067 PTE 0
[  183.638144] Oops: 0000 [#2] PREEMPT SMP NOPTI
[  183.638201] CPU: 3 PID: 1790 Comm: poc Tainted: G      D           5.17.0-rc6-ci-drm-11296+ #1
[  183.638298] Hardware name: Intel Corporation CoffeeLake Client Platform/CoffeeLake H DDR4 RVP, BIOS CNLSFWR1.R00.X208.B00.1905301319 05/30/2019
[  183.638430] RIP: 0010:memcpy_erms+0x6/0x10
[  183.640213] RSP: 0018:ffffc90001763d48 EFLAGS: 00010246
[  183.641117] RAX: ffff888109c14000 RBX: ffff888111bece40 RCX: 0000000000000ffc
[  183.642029] RDX: 0000000000001000 RSI: ffffc90000c86000 RDI: ffff888109c14004
[  183.642946] RBP: 0000000000000ffc R08: 800000000000016b R09: 0000000000000000
[  183.643848] R10: ffffc90000c85000 R11: 0000000000000048 R12: 0000000000001000
[  183.644742] R13: ffff888111bed190 R14: ffff888109c14000 R15: 0000000000001000
[  183.645653] FS:  00007fe5ef807540(0000) GS:ffff88845b380000(0000) knlGS:0000000000000000
[  183.646570] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  183.647481] CR2: ffffc90000c86000 CR3: 000000010ff02006 CR4: 00000000003706e0
[  183.648384] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  183.649271] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  183.650142] Call Trace:
[  183.650988]  <TASK>
[  183.651793]  vm_access+0x1f0/0x2a0 [i915]
[  183.652726]  __access_remote_vm+0x224/0x380
[  183.653561]  mem_rw.isra.0+0xf9/0x190
[  183.654402]  vfs_read+0x9d/0x1b0
[  183.655238]  ksys_read+0x63/0xe0
[  183.656065]  do_syscall_64+0x38/0xc0
[  183.656882]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[  183.657663] RIP: 0033:0x7fe5ef725142
[  183.659351] RSP: 002b:00007ffe1e81c7e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[  183.660227] RAX: ffffffffffffffda RBX: 0000557055dfb780 RCX: 00007fe5ef725142
[  183.661104] RDX: 0000000000001000 RSI: 00007ffe1e81d880 RDI: 0000000000000005
[  183.661972] RBP: 00007ffe1e81e890 R08: 0000000000000030 R09: 0000000000000046
[  183.662832] R10: 0000557055dfc2e0 R11: 0000000000000246 R12: 0000557055dfb1c0
[  183.663691] R13: 00007ffe1e81e980 R14: 0000000000000000 R15: 0000000000000000
[  183.664566]  </TASK>

Signed-off-by: Mastan Katragadda <mastanx.katragadda at intel.com>
Suggested-by: Adam Zabrocki <adamza at microsoft.com>
Reported-by: Jackson Cody <cody.jackson at intel.com>
Cc: Chris Wilson <chris.p.wilson at intel.com>
Cc: Bloomfield Jon <jon.bloomfield at intel.com>
Cc: Dutt Sudeep <sudeep.dutt at intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_mman.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
index efe69d6b86f4..45913fa31e17 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
@@ -455,7 +455,9 @@ vm_access(struct vm_area_struct *area, unsigned long addr,
 		return -EACCES;
 
 	addr -= area->vm_start;
-	if (addr >= obj->base.size)
+	if (len < 1 || len > obj->base.size ||
+	    addr >= obj->base.size ||
+	    addr + len > obj->base.size)
 		return -EINVAL;
 
 	i915_gem_ww_ctx_init(&ww, true);
-- 
2.25.1