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| author | Vitaly Wool <vitalywool@gmail.com> | 2019-07-16 16:25:48 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-16 19:23:21 -0700 |
| commit | bb9a374dfa3a2f46581455ab66cd1d24c5e3d183 (patch) | |
| tree | 654cb71efb841e60b08a23e1f85899eefb1f9e9c | |
| parent | 50950626414a982c8ed539128c7f69a3d328a970 (diff) | |
| download | lwn-bb9a374dfa3a2f46581455ab66cd1d24c5e3d183.tar.gz lwn-bb9a374dfa3a2f46581455ab66cd1d24c5e3d183.zip | |
mm/z3fold: don't try to use buddy slots after free
As reported by Henry Burns:
Running z3fold stress testing with address sanitization showed zhdr->slots
was being used after it was freed.
z3fold_free(z3fold_pool, handle)
free_handle(handle)
kmem_cache_free(pool->c_handle, zhdr->slots)
release_z3fold_page_locked_list(kref)
__release_z3fold_page(zhdr, true)
zhdr_to_pool(zhdr)
slots_to_pool(zhdr->slots) *BOOM*
To fix this, add pointer to the pool back to z3fold_header and modify
zhdr_to_pool to return zhdr->pool.
Link: http://lkml.kernel.org/r/20190708134808.e89f3bfadd9f6ffd7eff9ba9@gmail.com
Fixes: 7c2b8baa61fe ("mm/z3fold.c: add structure for buddy handles")
Signed-off-by: Vitaly Wool <vitalywool@gmail.com>
Reported-by: Henry Burns <henryburns@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Jonathan Adams <jwadams@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/z3fold.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/mm/z3fold.c b/mm/z3fold.c index dfcd69d08c1e..304f2883cdb9 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -101,6 +101,7 @@ struct z3fold_buddy_slots { * @refcount: reference count for the z3fold page * @work: work_struct for page layout optimization * @slots: pointer to the structure holding buddy slots + * @pool: pointer to the containing pool * @cpu: CPU which this page "belongs" to * @first_chunks: the size of the first buddy in chunks, 0 if free * @middle_chunks: the size of the middle buddy in chunks, 0 if free @@ -114,6 +115,7 @@ struct z3fold_header { struct kref refcount; struct work_struct work; struct z3fold_buddy_slots *slots; + struct z3fold_pool *pool; short cpu; unsigned short first_chunks; unsigned short middle_chunks; @@ -320,6 +322,7 @@ static struct z3fold_header *init_z3fold_page(struct page *page, zhdr->start_middle = 0; zhdr->cpu = -1; zhdr->slots = slots; + zhdr->pool = pool; INIT_LIST_HEAD(&zhdr->buddy); INIT_WORK(&zhdr->work, compact_page_work); return zhdr; @@ -426,7 +429,7 @@ static enum buddy handle_to_buddy(unsigned long handle) static inline struct z3fold_pool *zhdr_to_pool(struct z3fold_header *zhdr) { - return slots_to_pool(zhdr->slots); + return zhdr->pool; } static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked) |