Messages in this thread Patch in this message | | | From | Geert Uytterhoeven <> | Date | Tue, 29 May 2018 09:47:17 +0200 | Subject | Re: [PATCH v2] powerpc/64: Fix build failure with GCC 8.1 |
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Hi Christophe,
CC Geoff
On Tue, May 29, 2018 at 8:03 AM, Christophe Leroy <christophe.leroy@c-s.fr> wrote: > CC arch/powerpc/kernel/nvram_64.o > arch/powerpc/kernel/nvram_64.c: In function 'nvram_create_partition': > arch/powerpc/kernel/nvram_64.c:1042:2: error: 'strncpy' specified bound 12 equals destination size [-Werror=stringop-truncation] > strncpy(new_part->header.name, name, 12); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > CC arch/powerpc/kernel/trace/ftrace.o > In function 'make_field', > inlined from 'ps3_repository_read_boot_dat_address' at arch/powerpc/platforms/ps3/repository.c:900:9: > arch/powerpc/platforms/ps3/repository.c:106:2: error: 'strncpy' output truncated before terminating nul copying 8 bytes from a string of the same length [-Werror=stringop-truncation] > strncpy((char *)&n, text, 8); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Thanks for your patch!
> --- a/arch/powerpc/kernel/nvram_64.c > +++ b/arch/powerpc/kernel/nvram_64.c > @@ -1039,7 +1039,7 @@ loff_t __init nvram_create_partition(const char *name, int sig, > new_part->index = free_part->index; > new_part->header.signature = sig; > new_part->header.length = size; > - strncpy(new_part->header.name, name, 12); > + memcpy(new_part->header.name, name, strnlen(name, sizeof(new_part->header.name)));
The comment for nvram_header.lgnth says:
/* Terminating null required only for names < 12 chars. */
This will not terminate the string with a zero (the struct is allocated with kmalloc). So the original code is correct, the new one isn't.
> new_part->header.checksum = nvram_checksum(&new_part->header); > > rc = nvram_write_header(new_part); > diff --git a/arch/powerpc/platforms/ps3/repository.c b/arch/powerpc/platforms/ps3/repository.c > index 50dbaf24b1ee..e49c887787c4 100644 > --- a/arch/powerpc/platforms/ps3/repository.c > +++ b/arch/powerpc/platforms/ps3/repository.c > @@ -101,9 +101,9 @@ static u64 make_first_field(const char *text, u64 index) > > static u64 make_field(const char *text, u64 index) > { > - u64 n; > + u64 n = 0; > > - strncpy((char *)&n, text, 8); > + memcpy((char *)&n, text, strnlen(text, sizeof(n)));
This changes behavior: strncpy() fills the remainder of the buffer with zeroes. I don't remember the details of the PS3 repository structure, but given this writes to a fixed size u64 buffer, I'd expect the PS3 hypervisor code to (1) rely on the zero padding, and (2) not need a zero terminator if there are 8 characters in the buffer, so probably the original code is correct, and the "fixed" code isn't.
Has this been tested on a PS3?
> return n + index; > }
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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