media: m5mols: fix off-by-one loop termination error

[ Upstream commit efbcbb12ee99f750c9f25c873b55ad774871de2a ]

The __find_restype() function loops over the m5mols_default_ffmt[]
array, and the termination condition ends up being wrong: instead of
stopping when the iterator becomes the size of the array it traverses,
it stops after it has already overshot the array.

Now, in practice this doesn't likely matter, because the code will
always find the entry it looks for, and will thus return early and never
hit that last extra iteration.

But it turns out that clang will unroll the loop fully, because it has
only two iterations (well, three due to the off-by-one bug), and then
clang will end up just giving up in the middle of the loop unrolling
when it notices that the code walks past the end of the array.

And that made 'objtool' very unhappy indeed, because the generated code
just falls off the edge of the universe, and ends up falling through to
the next function, causing this warning:

   drivers/media/i2c/m5mols/m5mols.o: warning: objtool: m5mols_set_fmt() falls through to next function m5mols_get_frame_desc()

Fix the loop ending condition.

Reported-by: Jens Axboe <axboe@kernel.dk>
Analyzed-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Analyzed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/linux-block/CAHk-=wgTSdKYbmB1JYM5vmHMcD9J9UZr0mn7BOYM_LudrP+Xvw@mail.gmail.com/
Fixes: f3e08500ecb8 ("[media] Add support for M-5MOLS 8 Mega Pixel camera ISP")
Cc: HeungJun, Kim <riverful.kim@samsung.com>
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/media/i2c/m5mols/m5mols_core.c b/drivers/media/i2c/m5mols/m5mols_core.c
index 21666d705e3724baf51ee3d01238fd25722f8af9..dcf9e4d4ee6b81d871fd805e1c1909cfedfe3fd1 100644 (file)
--- a/drivers/media/i2c/m5mols/m5mols_core.c
+++ b/drivers/media/i2c/m5mols/m5mols_core.c
@@ -488,7 +488,7 @@ static enum m5mols_restype __find_restype(u32 code)
        do {
                if (code == m5mols_default_ffmt[type].code)
                        return type;
-       } while (type++ != SIZE_DEFAULT_FFMT);
+       } while (++type != SIZE_DEFAULT_FFMT);
 
        return 0;
 }