Messages in this thread | | | Date | Wed, 15 Feb 2023 13:32:20 -0800 | From | Kees Cook <> | Subject | Re: [PATCH] [v2] scsi: ipr: work around fortify-string warning |
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On Tue, Feb 14, 2023 at 02:28:08PM +0100, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > The ipr_log_vpd_compact() function triggers a fortified memcpy() warning > about a potential string overflow with all versions of clang: > > In file included from drivers/scsi/ipr.c:43: > In file included from include/linux/string.h:254: > include/linux/fortify-string.h:520:4: error: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning] > __write_overflow_field(p_size_field, size); > ^ > include/linux/fortify-string.h:520:4: error: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning] > 2 errors generated. > > I don't see anything actually wrong with the function, but this is the > only instance I can reproduce of the fortification going wrong in the > kernel at the moment, so the easiest solution may be to rewrite the > function into something that does not trigger the warning. > > Instead of having a combined buffer for vendor/device/serial strings, > use three separate local variables and just truncate the whitespace > individually. > > Fixes: 8cf093e275d0 ("[SCSI] ipr: Improved dual adapter errors") > Cc: Kees Cook <keescook@chromium.org> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reproduced this locally -- I agree your fix looks like the best approach. I think Clang was seeing the old "i + 2" return as potentially overflowing in the case where there was no space-padding on any strings.
-- Kees Cook
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