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mm/cma.c: fail if fixed declaration can't be honored 

The description of cma_declare_contiguous() indicates that if the
'fixed' argument is true the reserved contiguous area must be exactly at
the address of the 'base' argument.

However, the function currently allows the 'base', 'size', and 'limit'
arguments to be silently adjusted to meet alignment constraints.  This
commit enforces the documented behavior through explicit checks that
return an error if the region does not fit within a specified region.

Link: http://lkml.kernel.org/r/1561422051-16142-1-git-send-email-opendmb@gmail.com
Fixes: 5ea3b1b2f8 ("cma: add placement specifier for "cma=" kernel parameter")
Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Cc: Yue Hu <huyue2@yulong.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Doug Berger 2019-07-16 16:26:24 -07:00 committed by Linus Torvalds
parent c92d2f3856
commit c633324e31
1 changed files with 13 additions and 0 deletions
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13
mm/cma.c
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@ -278,6 +278,12 @@ int __init cma_declare_contiguous(phys_addr_t base,
*/ */
alignment = max(alignment, (phys_addr_t)PAGE_SIZE << alignment = max(alignment, (phys_addr_t)PAGE_SIZE <<
max_t(unsigned long, MAX_ORDER - 1, pageblock_order)); max_t(unsigned long, MAX_ORDER - 1, pageblock_order));
if (fixed && base & (alignment - 1)) {
ret = -EINVAL;
pr_err("Region at %pa must be aligned to %pa bytes\n",
&base, &alignment);
goto err;
}
base = ALIGN(base, alignment); base = ALIGN(base, alignment);
size = ALIGN(size, alignment); size = ALIGN(size, alignment);
limit &= ~(alignment - 1); limit &= ~(alignment - 1);
@ -308,6 +314,13 @@ int __init cma_declare_contiguous(phys_addr_t base,
if (limit == 0 || limit > memblock_end) if (limit == 0 || limit > memblock_end)
limit = memblock_end; limit = memblock_end;
if (base + size > limit) {
ret = -EINVAL;
pr_err("Size (%pa) of region at %pa exceeds limit (%pa)\n",
&size, &base, &limit);
goto err;
}
/* Reserve memory */ /* Reserve memory */
if (fixed) { if (fixed) {
if (memblock_is_region_reserved(base, size) || if (memblock_is_region_reserved(base, size) ||