diff options
| author | Muchun Song <songmuchun@bytedance.com> | 2026-05-20 14:10:25 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-05-28 20:50:33 -0700 |
| commit | c0ca59beb5252ea2bd4fdaef009d003dedc2030e (patch) | |
| tree | b148caa0c31785911c99ddf005e54eabaf8d3e9b /mm | |
| parent | c0cafe24d3f6534294c4b2bc2d47734ff7cbd313 (diff) | |
| download | linux-next-history-c0ca59beb5252ea2bd4fdaef009d003dedc2030e.tar.gz | |
mm/cma_debug: fix invalid accesses for inactive CMA areas
cma_activate_area() can fail after allocating range bitmaps. Its cleanup
path frees those bitmaps, but only clears cma->count and
cma->available_count. It leaves cma->nranges and each range's count in
place, so cma_debugfs_init() can still register debugfs files for an area
that never activated successfully.
That exposes two problems. Reading the bitmap file can make debugfs walk
a freed range bitmap and trigger an invalid memory access. Reading
maxchunk can also take cma->lock even though that lock is initialized only
on the successful activation path.
Fix this by creating debugfs entries only for CMA areas that reached
CMA_ACTIVATED.
c009da4258f9 introduced the invalid access to bitmap file. 2e32b947606d
introduced the invalid access to cma->lock. This change applies to both
issues. So I added two Fixes tags.
Link: https://lore.kernel.org/20260520061025.3971821-1-songmuchun@bytedance.com
Fixes: c009da4258f9 ("mm, cma: support multiple contiguous ranges, if requested")
Fixes: 2e32b947606d ("mm: cma: add functions to get region pages counters")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Oscar Salvador (SUSE) <osalvador@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Frank van der Linden <fvdl@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Stefan Strogin <stefan.strogin@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/cma_debug.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/cma_debug.c b/mm/cma_debug.c index 5ae38f5abbcc1..523ba4a0f9f76 100644 --- a/mm/cma_debug.c +++ b/mm/cma_debug.c @@ -205,7 +205,8 @@ static int __init cma_debugfs_init(void) cma_debugfs_root = debugfs_create_dir("cma", NULL); for (i = 0; i < cma_area_count; i++) - cma_debugfs_add_one(&cma_areas[i], cma_debugfs_root); + if (test_bit(CMA_ACTIVATED, &cma_areas[i].flags)) + cma_debugfs_add_one(&cma_areas[i], cma_debugfs_root); return 0; } |