On Fri, 2024-04-05 at 14:30:04 UTC, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@xxxxxxxx> > > 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@xxxxxxxxxxxxxxx > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/fixes, thanks. Miquel
