On 12/5/24 01:08, Brian Norris wrote: > Hi Nilay, > > I see you didn't CC the maintainers for this file. You might consider > looking through: > https://www.kernel.org/doc/html/latest/process/submitting-patches.html > And: > > $ scripts/get_maintainer.pl -f kernel/padata.c > Steffen Klassert <steffen.klassert@xxxxxxxxxxx> (maintainer:PADATA PARALLEL EXECUTION MECHANISM) > Daniel Jordan <daniel.m.jordan@xxxxxxxxxx> (maintainer:PADATA PARALLEL EXECUTION MECHANISM) > linux-crypto@xxxxxxxxxxxxxxx (open list:PADATA PARALLEL EXECUTION MECHANISM) > linux-kernel@xxxxxxxxxxxxxxx (open list:PADATA PARALLEL EXECUTION MECHANISM) > > I'll leave the full contents intact below for their sake, with a few > inline comments as well: > > On Tue, Nov 12, 2024 at 06:11:24PM +0530, Nilay Shroff wrote: >> While building the powerpc code using gcc 13, I came across following >> errors generated for kernel/padata.c file: >> >> CC kernel/padata.o >> In file included from ./include/linux/string.h:390, >> from ./arch/powerpc/include/asm/paca.h:16, >> from ./arch/powerpc/include/asm/current.h:13, >> from ./include/linux/thread_info.h:23, >> from ./include/asm-generic/preempt.h:5, >> from ./arch/powerpc/include/generated/asm/preempt.h:1, >> from ./include/linux/preempt.h:79, >> from ./include/linux/spinlock.h:56, >> from ./include/linux/swait.h:7, >> from ./include/linux/completion.h:12, >> from kernel/padata.c:14: >> In function ‘bitmap_copy’, >> inlined from ‘cpumask_copy’ at ./include/linux/cpumask.h:839:2, >> inlined from ‘__padata_set_cpumasks’ at kernel/padata.c:730:2: >> ./include/linux/fortify-string.h:114:33: error: ‘__builtin_memcpy’ reading between 257 and 536870904 bytes from a region of size 256 [-Werror=stringop-overread] >> 114 | #define __underlying_memcpy __builtin_memcpy >> | ^ >> ./include/linux/fortify-string.h:633:9: note: in expansion of macro ‘__underlying_memcpy’ >> 633 | __underlying_##op(p, q, __fortify_size); \ >> | ^~~~~~~~~~~~~ >> ./include/linux/fortify-string.h:678:26: note: in expansion of macro ‘__fortify_memcpy_chk’ >> 678 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \ >> | ^~~~~~~~~~~~~~~~~~~~ >> ./include/linux/bitmap.h:259:17: note: in expansion of macro ‘memcpy’ >> 259 | memcpy(dst, src, len); >> | ^~~~~~ >> kernel/padata.c: In function ‘__padata_set_cpumasks’: >> kernel/padata.c:713:48: note: source object ‘pcpumask’ of size [0, 256] >> 713 | cpumask_var_t pcpumask, >> | ~~~~~~~~~~~~~~^~~~~~~~ >> In function ‘bitmap_copy’, >> inlined from ‘cpumask_copy’ at ./include/linux/cpumask.h:839:2, >> inlined from ‘__padata_set_cpumasks’ at kernel/padata.c:730:2: >> ./include/linux/fortify-string.h:114:33: error: ‘__builtin_memcpy’ reading between 257 and 536870904 bytes from a region of size 256 [-Werror=stringop-overread] >> 114 | #define __underlying_memcpy __builtin_memcpy >> | ^ >> ./include/linux/fortify-string.h:633:9: note: in expansion of macro ‘__underlying_memcpy’ >> 633 | __underlying_##op(p, q, __fortify_size); \ >> | ^~~~~~~~~~~~~ >> ./include/linux/fortify-string.h:678:26: note: in expansion of macro ‘__fortify_memcpy_chk’ >> 678 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \ >> | ^~~~~~~~~~~~~~~~~~~~ >> ./include/linux/bitmap.h:259:17: note: in expansion of macro ‘memcpy’ >> 259 | memcpy(dst, src, len); >> | ^~~~~~ >> kernel/padata.c: In function ‘__padata_set_cpumasks’: >> kernel/padata.c:713:48: note: source object ‘pcpumask’ of size [0, 256] >> 713 | cpumask_var_t pcpumask, >> | ~~~~~~~~~~~~~~^~~~~~~~ >> >> Apparentrly, above errors only menifests with GCC 13.x and config option >> CONFIG_FORTIFY_SOURCE. Furthermore, if I use gcc 11.x or gcc 12.x then I >> don't encounter above errors. Prima facie, these erros appear to be false- >> positive. Brian informed me that currently some efforts are underway by >> GCC developers to emit more verbose information when GCC detects string >> overflow errors and that might help to further narrow down the root cause >> of this error. So for now, silence these errors using -Wno-stringop- >> overread gcc option while building kernel/padata.c file until we find the >> root cause. > > You might consider running this paragraph through a spelling checker if you submit a > v2. > >> Link: https://lore.kernel.org/all/7cbbd751-8332-4ab2-afa7-8c353834772a@xxxxxxxxxxxxx/ >> Cc: briannorris@xxxxxxxxxxxx >> Cc: kees@xxxxxxxxxx >> Cc: nathan@xxxxxxxxxx >> Cc: yury.norov@xxxxxxxxx >> Cc: linux@xxxxxxxxxxxxxx >> Cc: gjoyce@xxxxxxx >> Signed-off-by: Nilay Shroff <nilay@xxxxxxxxxxxxx> >> --- >> kernel/Makefile | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/kernel/Makefile b/kernel/Makefile >> index 87866b037fbe..e5adba7a30f1 100644 >> --- a/kernel/Makefile >> +++ b/kernel/Makefile >> @@ -120,6 +120,7 @@ obj-$(CONFIG_CFI_CLANG) += cfi.o >> obj-$(CONFIG_PERF_EVENTS) += events/ >> >> obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o >> +CFLAGS_padata.o += $(call cc-disable-warning, stringop-overread) > > Personally, I'd recommend a comment here, noting that these warnings > seem to produce false positives on GCC 13+. But otherwise, this seems OK > to me: > > Reviewed-by: Brian Norris <briannorris@xxxxxxxxxxxx> > >> obj-$(CONFIG_PADATA) += padata.o >> obj-$(CONFIG_JUMP_LABEL) += jump_label.o >> obj-$(CONFIG_CONTEXT_TRACKING) += context_tracking.o >> -- >> 2.45.2 >> Thank you Brian for your review! I would incorporate all your comments and spin a new patch and send it out soon... --Nilay
