staging: vc04_services: fix pointer arithmetic in create_pagelist - #7593
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nolasoft wants to merge 1 commit into
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staging: vc04_services: fix pointer arithmetic in create_pagelist#7593nolasoft wants to merge 1 commit into
nolasoft wants to merge 1 commit into
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In the vmalloc path of create_pagelist(), the address passed to
vmalloc_to_page() was computed as:
(unsigned int *)bulk->offset + (actual_pages * PAGE_SIZE)
Because pointer arithmetic on unsigned int * scales by sizeof(unsigned int),
this advances by 4 * PAGE_SIZE bytes instead of PAGE_SIZE. As a result,
only the first page is correct; subsequent pages point to the wrong
addresses.
Cast through char * (or void *) so the offset is applied in bytes.
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Summary
Fix a pointer-arithmetic bug in the vmalloc handling path of
create_pagelist().Problem
In
drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c:Adding an integer to an unsigned int * multiplies the offset by sizeof(unsigned int) (4). Consequently the address becomes:bulk->offset + (actual_pages * PAGE_SIZE * 4)instead of the intended:bulk->offset + (actual_pages * PAGE_SIZE)Only the first page is correct; later pages are wrong. This can lead to
incorrect DMA mappings, data corruption, or NULL page pointers.