Le 29/05/2018 à 09:47, Geert Uytterhoeven a écrit :

Hi Christophe,

CC Geoff

On Tue, May 29, 2018 at 8:03 AM, Christophe Leroy
[off-list ref] wrote:

quoted

   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 <redacted>

Thanks for your patch!

quoted

--- 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.

Right, then I have to first zeroize the destination.

quoted

         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.

Here I have set n to 0 prior to the copy, so the buffer IS zero padded.

Christophe

Has this been tested on a PS3?

quoted

         return n + index;
  }

Gr{oetje,eeting}s,

                         Geert