Messages in this thread | | | From | Dan Williams <> | Date | Wed, 24 Mar 2021 12:08:20 -0700 | Subject | Re: [PATCH] cxl/mem: Force array size of mem_commands[] to CXL_MEM_COMMAND_ID_MAX |
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On Wed, Mar 24, 2021 at 11:43 AM Ira Weiny <ira.weiny@intel.com> wrote: > > On Wed, Mar 24, 2021 at 03:16:35PM +0100, Robert Richter wrote: > > Typically the mem_commands[] array is in sync with 'enum { CXL_CMDS }'. > > Current code works well. > > > > However, the array size of mem_commands[] may not strictly be the same > > as CXL_MEM_COMMAND_ID_MAX. E.g. if a new CXL_CMD() is added that is > > guarded by #ifdefs, the array could be shorter. This could lead then > > further to an out-of-bounds array access in cxl_validate_cmd_from_user(). > > > > Fix this by forcing the array size to CXL_MEM_COMMAND_ID_MAX. This > > also adds range checks for array items in mem_commands[] at compile > > time. > > Can't we use ARRAY_SIZE?
An ARRAY_SIZE() check in cxl_validate_cmd_from_user() would work too, but it wouldn't give the compiler protection that Robert mentions for going the other way where mem_commands tries to add an entry that is out of bounds relative to CXL_CMDS.
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