From c0837b9cf6eabbad8b8cbddaff1a46a6d0a2e29d Mon Sep 17 00:00:00 2001 From: Muhammad Bilal Date: Sat, 23 May 2026 19:08:43 +0000 Subject: [PATCH] accel/ethosu: fix OOB write in ethosu_gem_cmdstream_copy_and_validate() The command stream parsing loop increments the index variable a second time when a 64-bit command word is encountered (bit 14 set), but does not re-check the loop bound before writing the second word: for (i = 0; i < size / 4; i++) { bocmds[i] = cmds[0]; if (cmd & 0x4000) { i++; bocmds[i] = cmds[1]; /* unchecked */ } } The buffer bocmds is backed by a DMA allocation of exactly size bytes from drm_gem_dma_create(ddev, size), giving valid indices [0, size/4-1]. When i == size/4 - 1 on entry to an iteration and bit 14 of cmds[0] is set, bocmds[size/4-1] is written in bounds, i is then incremented to size/4, and bocmds[size/4] writes four bytes past the end of the allocation. Userspace controls both the buffer contents and the size argument via the ioctl, making this a userspace-triggerable heap out-of-bounds write. Fix by checking the incremented index against the buffer bound before the second write and returning -EINVAL if the buffer is too small to contain the extended command. Fixes: 5a5e9c0228e6 ("accel: Add Arm Ethos-U NPU driver") Cc: stable@vger.kernel.org Signed-off-by: Muhammad Bilal Link: https://patch.msgid.link/20260523190843.33977-1-meatuni001@gmail.com Signed-off-by: Rob Herring (Arm) --- drivers/accel/ethosu/ethosu_gem.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/accel/ethosu/ethosu_gem.c b/drivers/accel/ethosu/ethosu_gem.c index 2cb7964ddfa5..3401883e207f 100644 --- a/drivers/accel/ethosu/ethosu_gem.c +++ b/drivers/accel/ethosu/ethosu_gem.c @@ -401,6 +401,8 @@ static int ethosu_gem_cmdstream_copy_and_validate(struct drm_device *ddev, return -EFAULT; i++; + if (i >= size / 4) + return -EINVAL; bocmds[i] = cmds[1]; addr = cmd_to_addr(cmds); } -- 2.47.3