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mm/highmem: VM_BUG_ON() if offset + len > PAGE_SIZE

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Add VM_BUG_ON() bounds checking to make sure that, if "offset + len>
PAGE_SIZE", memset() does not corrupt data in adjacent pages.

Mainly to match all the similar functions in highmem.h.

Link: https://lkml.kernel.org/r/20220426193020.8710-1-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Peter Collingbourne <pcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Fabio M. De Francesco 2022-05-09 18:20:51 -07:00 committed by Andrew Morton
parent 3c81b3bb0a
commit f38adfef7e
1 changed files with 2 additions and 0 deletions
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2
include/linux/highmem.h
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@ -358,6 +358,8 @@ static inline void memcpy_to_page(struct page *page, size_t offset,
static inline void memzero_page(struct page *page, size_t offset, size_t len)
{
char *addr = kmap_local_page(page);
VM_BUG_ON(offset + len > PAGE_SIZE);
memset(addr + offset, 0, len);
flush_dcache_page(page);
kunmap_local(addr);