linux.git/drivers/accel/ethosu/ethosu_gem.c, branch master

accel: ethosu: Handle U85 internal chaining buffer

2026-07-21T20:21:56Z

The Ethos-U85 supports an internal chaining buffer as temporary storage between some operations. When chaining is activated, the IFM/OFM region setting selects a chaining buffer rather than a region, and the IFM/OFM base addresses don't matter. In this case, the feature matrix size calculations should be skipped. Otherwise, the command stream will be intermittently rejected depending on prior feature matrix base addresses. Fixes: 5a5e9c0228e6 ("accel: Add Arm Ethos-U NPU driver") Acked-by: Tomeu Vizoso Link: https://patch.msgid.link/20260720231450.485221-2-robh@kernel.org Signed-off-by: Rob Herring (Arm)

accel: ethosu: Fix element size accounting for cmd stream validation

2026-07-21T20:21:56Z

There are 2 issues with the element size handling in the command stream validation which result in too small of a size calculated when the element size is 16/32/64 bits. For NHWC format, the element size is simply missing from the calculation. The bitfield for the element size is different between IFM/IFM2 and OFM. IFM and IFM2 encode the precision in parameter bits 2:3, while OFM uses bits 1:2. Fixes: 5a5e9c0228e6 ("accel: Add Arm Ethos-U NPU driver") Acked-by: Tomeu Vizoso Link: https://patch.msgid.link/20260720231450.485221-1-robh@kernel.org Signed-off-by: Rob Herring (Arm)

accel/ethosu: fix OOB write in ethosu_gem_cmdstream_copy_and_validate()

2026-06-05T03:07:59Z

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)

accel/ethosu: reject DMA commands with uninitialized length

2026-06-04T22:43:43Z

cmd_state_init() initializes the command state with memset(0xff), leaving dma->len at U64_MAX to signal missing setup. The only setter is NPU_SET_DMA0_LEN; if userspace omits this command and issues NPU_OP_DMA_START, dma->len remains U64_MAX. In dma_length(), a positive stride added to U64_MAX wraps to a small value. With size0 == 1, check_mul_overflow() does not trigger and dma_length() returns 0 instead of U64_MAX. The caller's U64_MAX check then passes, region_size[] stays 0, and the bounds check in ethosu_job.c is bypassed, allowing hardware to execute DMA with stale physical addresses. Fix by checking for U64_MAX at the start of dma_length() before any arithmetic, consistent with the sentinel value used throughout the driver to detect uninitialized fields. Fixes: 5a5e9c0228e6 ("accel: Add Arm Ethos-U NPU driver") Cc: stable@vger.kernel.org Signed-off-by: Muhammad Bilal Link: https://patch.msgid.link/20260524130319.12747-1-meatuni001@gmail.com Signed-off-by: Rob Herring (Arm)

accel/ethosu: fix arithmetic issues in dma_length()

2026-06-04T22:43:27Z

dma_length() derives DMA region usage from command stream values and updates region_size[]: len = ((len + stride[0]) * size0 + stride[1]) * size1 region_size[region] = max(..., len + dma->offset) Several arithmetic issues can corrupt the derived region size: - signed stride values may underflow when added to len - intermediate multiplications may overflow - len + dma->offset may overflow during region_size updates - dma_length() error returns were not validated by the caller region_size[] is later used by ethosu_job.c to validate command stream accesses against GEM buffer sizes. Arithmetic wraparound can therefore under-report region usage and bypass the bounds validation. Fix by validating signed additions, using overflow helpers for multiplications and offset updates, and propagating dma_length() failures to the caller. Fixes: 5a5e9c0228e6 ("accel: Add Arm Ethos-U NPU driver") Cc: stable@vger.kernel.org Signed-off-by: Muhammad Bilal Link: https://patch.msgid.link/20260524103710.47397-1-meatuni001@gmail.com Signed-off-by: Rob Herring (Arm)

accel/ethosu: fix wrong weight index in NPU_SET_SCALE1_LENGTH on U85

2026-06-04T22:41:46Z

On non-U65 hardware (e.g. U85), opcode 0x4093 is NPU_SET_WEIGHT2_LENGTH. The BASE handler for the same opcode correctly assigns to st.weight[2].base, but the LENGTH handler mistakenly assigns cmds[1] to st.weight[1].length instead of st.weight[2].length. This leaves weight[2].length at its initialised sentinel value of 0xffffffff and corrupts weight[1].length with the user-supplied value, breaking the software bounds-check state for both weight buffers on U85. Fix the index to match the BASE handler. Fixes: 5a5e9c0228e6 ("accel: Add Arm Ethos-U NPU driver") Cc: stable@vger.kernel.org Signed-off-by: Muhammad Bilal Link: https://patch.msgid.link/20260523210840.92039-3-meatuni001@gmail.com Signed-off-by: Rob Herring (Arm)

accel/ethosu: reject NPU_OP_RESIZE commands from userspace

2026-06-04T22:41:46Z

NPU_OP_RESIZE is a U85-only command that the driver does not yet implement. The existing WARN_ON(1) placeholder fires unconditionally whenever userspace submits this command via DRM_IOCTL_ETHOSU_GEM_CREATE, causing unbounded kernel log spam. If panic_on_warn is set the kernel panics, giving any unprivileged user with access to the DRM device a trivial denial-of-service primitive. Replace the WARN_ON(1) with an explicit -EINVAL return so the ioctl rejects the command before it reaches hardware. Fixes: 5a5e9c0228e6 ("accel: Add Arm Ethos-U NPU driver") Cc: stable@vger.kernel.org Signed-off-by: Muhammad Bilal Link: https://patch.msgid.link/20260523210840.92039-2-meatuni001@gmail.com Signed-off-by: Rob Herring (Arm)

accel/ethosu: fix IFM region index out-of-bounds in command stream parser

2026-06-04T22:31:41Z

NPU_SET_IFM_REGION extracts the region index with param & 0x7f, giving a maximum value of 127. However region_size[] and output_region[] in struct ethosu_validated_cmdstream_info are both sized to NPU_BASEP_REGION_MAX (8), giving valid indices [0..7]. Every other region assignment in the same switch uses param & 0x7: NPU_SET_OFM_REGION: st.ofm.region = param & 0x7; NPU_SET_IFM2_REGION: st.ifm2.region = param & 0x7; NPU_SET_WEIGHT_REGION: st.weight[0].region = param & 0x7; NPU_SET_SCALE_REGION: st.scale[0].region = param & 0x7; The 0x7f mask on IFM is inconsistent and appears to be a typo. feat_matrix_length() and calc_sizes() use the region index directly as an array subscript into the kzalloc'd info struct: info->region_size[fm->region] = max(...); A userspace caller supplying NPU_SET_IFM_REGION with param > 7 causes a write up to 127*8 = 1016 bytes past the start of region_size[], corrupting adjacent kernel heap data. Fix by applying the same & 0x7 mask used by all other region assignments. Fixes: 5a5e9c0228e6 ("accel: Add Arm Ethos-U NPU driver") Cc: stable@vger.kernel.org Signed-off-by: Muhammad Bilal Link: https://patch.msgid.link/20260523195159.55801-1-meatuni001@gmail.com Signed-off-by: Rob Herring (Arm)

accel: ethosu: Handle possible underflow in IFM size calculations

2026-03-05T21:21:17Z

If the command stream has larger padding sizes than the IFM and OFM diminsions, then the calculations will underflow to a negative value. The result is a very large region bounds which is caught on submit, but it's better to catch it earlier. Current mesa ethosu driver has a signedness bug which resulted in padding of 127 (the max) and triggers this issue. Reviewed-and-Tested-by: Anders Roxell Link: https://patch.msgid.link/20260218-ethos-fixes-v1-3-be3fa3ea9a30@kernel.org Signed-off-by: Rob Herring (Arm)

accel: ethosu: Fix NPU_OP_ELEMENTWISE validation with scalar

2026-03-05T21:21:17Z

The NPU_OP_ELEMENTWISE instruction uses a scalar value for IFM2 if the IFM2_BROADCAST "scalar" mode is set. It is a bit (7) on the u65 and part of a field (bits 3:0) on the u85. The driver was hardcoded to the u85. Fixes: 5a5e9c0228e6 ("accel: Add Arm Ethos-U NPU driver") Reviewed-and-Tested-by: Anders Roxell Link: https://patch.msgid.link/20260218-ethos-fixes-v1-2-be3fa3ea9a30@kernel.org Signed-off-by: Rob Herring (Arm)