[ Upstream commit c633324e311243586675e732249339685e5d6faa ]
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: 5ea3b1b2f8ad ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- mm/cma.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/mm/cma.c b/mm/cma.c index 4ea0f32761c1a..7cb569a188c48 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -268,6 +268,12 @@ int __init cma_declare_contiguous(phys_addr_t base, */ alignment = max(alignment, (phys_addr_t)PAGE_SIZE << 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); size = ALIGN(size, alignment); limit &= ~(alignment - 1); @@ -298,6 +304,13 @@ int __init cma_declare_contiguous(phys_addr_t base, if (limit == 0 || 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 */ if (fixed) { if (memblock_is_region_reserved(base, size) ||