On Fri, 2024-04-05 at 14:30:04 UTC, Arnd Bergmann wrote:
From: Arnd Bergmann arnd@arndb.de
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
Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/fixes, thanks.
Miquel