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common/memsize.c: Fix get_effective_memsize() to check for overflow

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Ensure that top of RAM can be represented by phys_size_t type. If RAM is
too large or RAM base address is too upper then limit RAM size to prevent
address space overflow.

Signed-off-by: Pali Rohár <pali@kernel.org>
This commit is contained in:
Pali Rohár 2022-09-09 17:32:39 +02:00 committed by Tom Rini
parent 7210e457d5
commit 777aaaa706
1 changed files with 15 additions and 3 deletions
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18
common/memsize.c
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@ -94,11 +94,23 @@ long get_ram_size(long *base, long maxsize)
phys_size_t __weak get_effective_memsize(void)
{
phys_size_t ram_size = gd->ram_size;
/*
* Check for overflow and limit ram size to some representable value.
* It is required that ram_base + ram_size must be representable by
* phys_size_t type and must be aligned by direct access, therefore
* calculate it from last 4kB sector which should work as alignment
* on any platform.
*/
if (gd->ram_base + ram_size < gd->ram_base)
ram_size = ((phys_size_t)~0xfffULL) - gd->ram_base;
#ifndef CONFIG_MAX_MEM_MAPPED
return gd->ram_size;
return ram_size;
#else
/* limit stack to what we can reasonable map */
return ((gd->ram_size > CONFIG_MAX_MEM_MAPPED) ?
CONFIG_MAX_MEM_MAPPED : gd->ram_size);
return ((ram_size > CONFIG_MAX_MEM_MAPPED) ?
CONFIG_MAX_MEM_MAPPED : ram_size);
#endif
}