diff options
| author | Waiman Long <longman@redhat.com> | 2022-04-08 13:09:01 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-15 14:18:40 +0200 |
| commit | fdfb9ae26161606952f4cc3c4e0c0984d5c81cb6 (patch) | |
| tree | 42001a1a7f826aa377d6787cb11bdfa2179d3265 /include/linux | |
| parent | a0c0867f06b9c8bae2b8164fe7b581c250a1c9c6 (diff) | |
mm/sparsemem: fix 'mem_section' will never be NULL gcc 12 warning
commit a431dbbc540532b7465eae4fc8b56a85a9fc7d17 upstream.
The gcc 12 compiler reports a "'mem_section' will never be NULL" warning
on the following code:
static inline struct mem_section *__nr_to_section(unsigned long nr)
{
#ifdef CONFIG_SPARSEMEM_EXTREME
if (!mem_section)
return NULL;
#endif
if (!mem_section[SECTION_NR_TO_ROOT(nr)])
return NULL;
:
It happens with CONFIG_SPARSEMEM_EXTREME off. The mem_section definition
is
#ifdef CONFIG_SPARSEMEM_EXTREME
extern struct mem_section **mem_section;
#else
extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
#endif
In the !CONFIG_SPARSEMEM_EXTREME case, mem_section is a static
2-dimensional array and so the check "!mem_section[SECTION_NR_TO_ROOT(nr)]"
doesn't make sense.
Fix this warning by moving the "!mem_section[SECTION_NR_TO_ROOT(nr)]"
check up inside the CONFIG_SPARSEMEM_EXTREME block and adding an
explicit NR_SECTION_ROOTS check to make sure that there is no
out-of-bound array access.
Link: https://lkml.kernel.org/r/20220331180246.2746210-1-longman@redhat.com
Fixes: 3e347261a80b ("sparsemem extreme implementation")
Signed-off-by: Waiman Long <longman@redhat.com>
Reported-by: Justin Forbes <jforbes@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/mmzone.h | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index bc8a70a7c5a1..e4f9df955040 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1250,13 +1250,16 @@ static inline unsigned long *section_to_usemap(struct mem_section *ms) static inline struct mem_section *__nr_to_section(unsigned long nr) { + unsigned long root = SECTION_NR_TO_ROOT(nr); + + if (unlikely(root >= NR_SECTION_ROOTS)) + return NULL; + #ifdef CONFIG_SPARSEMEM_EXTREME - if (!mem_section) + if (!mem_section || !mem_section[root]) return NULL; #endif - if (!mem_section[SECTION_NR_TO_ROOT(nr)]) - return NULL; - return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK]; + return &mem_section[root][nr & SECTION_ROOT_MASK]; } extern unsigned long __section_nr(struct mem_section *ms); extern size_t mem_section_usage_size(void); |