diff options
| author |   Liam R. Howlett <Liam.Howlett@oracle.com> | 2025-06-16 14:45:20 -0400 |
|---|---|---|
| committer |   Andrew Morton <akpm@linux-foundation.org> | 2025-06-19 20:48:04 -0700 |
| commit | fba46a5d83ca8decb338722fb4899026d8d9ead2 (patch) | |
| tree | 775fed388841ce113a910bd9da2c4111803e8871 | |
| parent | MAINTAINERS: add missing test files to mm gup section (diff) | |
| download | wireguard-linux-fba46a5d83ca8decb338722fb4899026d8d9ead2.tar.xz wireguard-linux-fba46a5d83ca8decb338722fb4899026d8d9ead2.zip | |
maple_tree: fix MA_STATE_PREALLOC flag in mas_preallocate()
Temporarily clear the preallocation flag when explicitly requesting
allocations. Pre-existing allocations are already counted against the
request through mas_node_count_gfp(), but the allocations will not happen
if the MA_STATE_PREALLOC flag is set. This flag is meant to avoid
re-allocating in bulk allocation mode, and to detect issues with
preallocation calculations.
The MA_STATE_PREALLOC flag should also always be set on zero allocations
so that detection of underflow allocations will print a WARN_ON() during
consumption.
User visible effect of this flaw is a WARN_ON() followed by a null pointer
dereference when subsequent requests for larger number of nodes is
ignored, such as the vma merge retry in mmap_region() caused by drivers
altering the vma flags (which happens in v6.6, at least)
Link: https://lkml.kernel.org/r/20250616184521.3382795-3-Liam.Howlett@oracle.com
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reported-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
Reported-by: Hailong Liu <hailong.liu@oppo.com>
Link: https://lore.kernel.org/all/1652f7eb-a51b-4fee-8058-c73af63bacd1@oppo.com/
Link: https://lore.kernel.org/all/20250428184058.1416274-1-Liam.Howlett@oracle.com/
Link: https://lore.kernel.org/all/20250429014754.1479118-1-Liam.Howlett@oracle.com/
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Hailong Liu <hailong.liu@oppo.com>
Cc: zhangpeng.00@bytedance.com <zhangpeng.00@bytedance.com>
Cc: Steve Kang <Steve.Kang@unisoc.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | lib/maple_tree.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/lib/maple_tree.c b/lib/maple_tree.c index affe979bd14d..00524e55a21e 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -5527,8 +5527,9 @@ int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp) mas->store_type = mas_wr_store_type(&wr_mas); request = mas_prealloc_calc(&wr_mas, entry); if (!request) - return ret; + goto set_flag; + mas->mas_flags &= ~MA_STATE_PREALLOC; mas_node_count_gfp(mas, request, gfp); if (mas_is_err(mas)) { mas_set_alloc_req(mas, 0); @@ -5538,6 +5539,7 @@ int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp) return ret; } +set_flag: mas->mas_flags |= MA_STATE_PREALLOC; return ret; } |