drm/i915/dmc: protect against reading random memory
While loading the DMC firmware we were double checking the headers made sense, but in no place we checked that we were actually reading memory we were supposed to. This could be wrong in case the firmware file is truncated or malformed. Before this patch: # ls -l /lib/firmware/i915/icl_dmc_ver1_07.bin -rw-r--r-- 1 root root 25716 Feb 1 12:26 icl_dmc_ver1_07.bin # truncate -s 25700 /lib/firmware/i915/icl_dmc_ver1_07.bin # modprobe i915 # dmesg| grep -i dmc [drm:intel_csr_ucode_init [i915]] Loading i915/icl_dmc_ver1_07.bin [drm] Finished loading DMC firmware i915/icl_dmc_ver1_07.bin (v1.7) i.e. it loads random data. Now it fails like below: [drm:intel_csr_ucode_init [i915]] Loading i915/icl_dmc_ver1_07.bin [drm:csr_load_work_fn [i915]] *ERROR* Truncated DMC firmware, rejecting. i915 0000:00:02.0: Failed to load DMC firmware i915/icl_dmc_ver1_07.bin. Disabling runtime power management. i915 0000:00:02.0: DMC firmware homepage: https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/tree/i915 Before reading any part of the firmware file, validate the input first. Fixes: eb805623 ("drm/i915/skl: Add support to load SKL CSR firmware.") Cc: stable@vger.kernel.org Signed-off-by:Lucas De Marchi <lucas.demarchi@intel.com> Reviewed-by:
Rodrigo Vivi <rodrigo.vivi@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190605235535.17791-1-lucas.demarchi@intel.com
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