Messages in this thread | | | Date | Tue, 2 Nov 2021 07:26:20 -0700 | From | Guenter Roeck <> | Subject | Re: [PATCH] string: uninline memcpy_and_pad |
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Scratch this one. Forgot v2 in subject. Resending, and sorry for the noise.
Guenter
On Tue, Nov 02, 2021 at 07:24:20AM -0700, Guenter Roeck wrote: > When building m68k:allmodconfig, recent versions of gcc generate the > following error if the length of UTS_RELEASE is less than 8 bytes. > > In function 'memcpy_and_pad', > inlined from 'nvmet_execute_disc_identify' at > drivers/nvme/target/discovery.c:268:2: > arch/m68k/include/asm/string.h:72:25: error: > '__builtin_memcpy' reading 8 bytes from a region of size 7 > > Discussions around the problem suggest that this only happens if an > architecture does not provide strlen(), if -ffreestanding is provided as > compiler option, and if CONFIG_FORTIFY_SOURCE=n. All of this is the case > for m68k. The exact reasons are unknown, but seem to be related to the > ability of the compiler to evaluate the return value of strlen() and > the resulting execution flow in memcpy_and_pad(). It would be possible > to work around the problem by using sizeof(UTS_RELEASE) instead of > strlen(UTS_RELEASE), but that would only postpone the problem until the > function is called in a similar way. Uninline memcpy_and_pad() instead > to solve the problem for good. > > Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> > Cc: Geert Uytterhoeven <geert@linux-m68k.org> > Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> > Acked-by: Andy Shevchenko <andriy.shevchenko@intel.com> > Signed-off-by: Guenter Roeck <linux@roeck-us.net> > --- > v2: Moved to lib/string_helpers.c > Balanced { } in if/else statement to make checkpatch happy > Added Reviewed-by: /Acked-by: tags > > include/linux/string.h | 19 ++----------------- > lib/string_helpers.c | 20 ++++++++++++++++++++ > 2 files changed, 22 insertions(+), 17 deletions(-) > > diff --git a/include/linux/string.h b/include/linux/string.h > index 5a36608144a9..b6572aeca2f5 100644 > --- a/include/linux/string.h > +++ b/include/linux/string.h > @@ -253,23 +253,8 @@ static inline const char *kbasename(const char *path) > #include <linux/fortify-string.h> > #endif > > -/** > - * memcpy_and_pad - Copy one buffer to another with padding > - * @dest: Where to copy to > - * @dest_len: The destination buffer size > - * @src: Where to copy from > - * @count: The number of bytes to copy > - * @pad: Character to use for padding if space is left in destination. > - */ > -static inline void memcpy_and_pad(void *dest, size_t dest_len, > - const void *src, size_t count, int pad) > -{ > - if (dest_len > count) { > - memcpy(dest, src, count); > - memset(dest + count, pad, dest_len - count); > - } else > - memcpy(dest, src, dest_len); > -} > +void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count, > + int pad); > > /** > * memset_after - Set a value after a struct member to the end of a struct > diff --git a/lib/string_helpers.c b/lib/string_helpers.c > index faa9d8e4e2c5..d5d008f5b1d9 100644 > --- a/lib/string_helpers.c > +++ b/lib/string_helpers.c > @@ -883,6 +883,26 @@ char *strreplace(char *s, char old, char new) > } > EXPORT_SYMBOL(strreplace); > > +/** > + * memcpy_and_pad - Copy one buffer to another with padding > + * @dest: Where to copy to > + * @dest_len: The destination buffer size > + * @src: Where to copy from > + * @count: The number of bytes to copy > + * @pad: Character to use for padding if space is left in destination. > + */ > +void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count, > + int pad) > +{ > + if (dest_len > count) { > + memcpy(dest, src, count); > + memset(dest + count, pad, dest_len - count); > + } else { > + memcpy(dest, src, dest_len); > + } > +} > +EXPORT_SYMBOL(memcpy_and_pad); > + > #ifdef CONFIG_FORTIFY_SOURCE > void fortify_panic(const char *name) > { > -- > 2.33.0 >
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