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| author |   Gao Xiang <hsiangkao@redhat.com> | 2020-06-19 07:43:49 +0800 |
|---|---|---|
| committer | Gao Xiang <hsiangkao@redhat.com> | 2020-06-24 09:47:44 +0800 |
| commit | 3c597282887fd55181578996dca52ce697d985a5 (patch) | |
| tree | f4c82f3cc413ff2bcafa43debfa3e0e07cd14081 /fs/erofs | |
| parent | Linux 5.8-rc1 (diff) | |
| download | linux-dev-3c597282887fd55181578996dca52ce697d985a5.tar.xz linux-dev-3c597282887fd55181578996dca52ce697d985a5.zip | |
erofs: fix partially uninitialized misuse in z_erofs_onlinepage_fixup
Hongyu reported "id != index" in z_erofs_onlinepage_fixup() with
specific aarch64 environment easily, which wasn't shown before.
After digging into that, I found that high 32 bits of page->private
was set to 0xaaaaaaaa rather than 0 (due to z_erofs_onlinepage_init
behavior with specific compiler options). Actually we only use low
32 bits to keep the page information since page->private is only 4
bytes on most 32-bit platforms. However z_erofs_onlinepage_fixup()
uses the upper 32 bits by mistake.
Let's fix it now.
Reported-and-tested-by: Hongyu Jin <hongyu.jin@unisoc.com>
Fixes: 3883a79abd02 ("staging: erofs: introduce VLE decompression support")
Cc: <stable@vger.kernel.org> # 4.19+
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20200618234349.22553-1-hsiangkao@aol.com
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Diffstat (limited to 'fs/erofs')
| -rw-r--r-- | fs/erofs/zdata.h | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/fs/erofs/zdata.h b/fs/erofs/zdata.h index 7824f5563a55..9b66c28b3ae9 100644 --- a/fs/erofs/zdata.h +++ b/fs/erofs/zdata.h @@ -144,22 +144,22 @@ static inline void z_erofs_onlinepage_init(struct page *page) static inline void z_erofs_onlinepage_fixup(struct page *page, uintptr_t index, bool down) { - unsigned long *p, o, v, id; -repeat: - p = &page_private(page); - o = READ_ONCE(*p); + union z_erofs_onlinepage_converter u = { .v = &page_private(page) }; + int orig, orig_index, val; - id = o >> Z_EROFS_ONLINEPAGE_INDEX_SHIFT; - if (id) { +repeat: + orig = atomic_read(u.o); + orig_index = orig >> Z_EROFS_ONLINEPAGE_INDEX_SHIFT; + if (orig_index) { if (!index) return; - DBG_BUGON(id != index); + DBG_BUGON(orig_index != index); } - v = (index << Z_EROFS_ONLINEPAGE_INDEX_SHIFT) | - ((o & Z_EROFS_ONLINEPAGE_COUNT_MASK) + (unsigned int)down); - if (cmpxchg(p, o, v) != o) + val = (index << Z_EROFS_ONLINEPAGE_INDEX_SHIFT) | + ((orig & Z_EROFS_ONLINEPAGE_COUNT_MASK) + (unsigned int)down); + if (atomic_cmpxchg(u.o, orig, val) != orig) goto repeat; } |