tree 3ff95614a7ed6eb00a2400e47fb970d88ff7ce1c
parent 9485c0dda576f58a9579b81e4d10b72bebda58de
author Arnd Bergmann <arnd@arndb.de> 1712327404 +0200
committer Vegard Nossum <vegard.nossum@oracle.com> 1717160248 +0000

mtd: diskonchip: work around ubsan link failure

commit 21c9fb611c25d5cd038f6fe485232e7884bb0b3d upstream.

I ran into a randconfig build failure with UBSAN using gcc-13.2:

arm-linux-gnueabi-ld: error: unplaced orphan section `.bss..Lubsan_data31' from `drivers/mtd/nand/raw/diskonchip.o'

I'm not entirely sure what is going on here, but I suspect this has something
to do with the check for the end of the doc_locations[] array that contains
an (unsigned long)0xffffffff element, which is compared against the signed
(int)0xffffffff. If this is the case, we should get a runtime check for
undefined behavior, but we instead get an unexpected build-time error.

I would have expected this to work fine on 32-bit architectures despite the
signed integer overflow, though on 64-bit architectures this likely won't
ever work.

Changing the contition to instead check for the size of the array makes the
code safe everywhere and avoids the ubsan check that leads to the link
error. The loop code goes back to before 2.6.12.

Cc: stable@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20240405143015.717429-1-arnd@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 153adb5d7878d18e2b9be173996034f858fbce8e)
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>