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pstore/ram_core: Better ECC size checking

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- Instead of exploiting unsigned overflows (which doesn't work for all
  sizes), use straightforward checking for ECC total size not exceeding
  initial buffer size;

- Printing overflowed buffer_size is not informative. Instead, print
  ecc_size and buffer_size;

- No need for buffer_size argument in persistent_ram_init_ecc(),
  we can address prz->buffer_size directly.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Anton Vorontsov 2012-06-18 19:15:53 -07:00 committed by Greg Kroah-Hartman
parent beeb94321a
commit 1e6a9e5625
1 changed files with 8 additions and 8 deletions
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16
fs/pstore/ram_core.c
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@ -171,12 +171,12 @@ static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
}
}
static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
size_t buffer_size)
static int persistent_ram_init_ecc(struct persistent_ram_zone *prz)
{
int numerr;
struct persistent_ram_buffer *buffer = prz->buffer;
int ecc_blocks;
size_t ecc_total;
if (!prz->ecc)
return 0;
@ -187,14 +187,14 @@ static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
prz->ecc_poly = 0x11d;
ecc_blocks = DIV_ROUND_UP(prz->buffer_size, prz->ecc_block_size);
prz->buffer_size -= (ecc_blocks + 1) * prz->ecc_size;
if (prz->buffer_size > buffer_size) {
pr_err("persistent_ram: invalid size %zu, non-ecc datasize %zu\n",
buffer_size, prz->buffer_size);
ecc_total = (ecc_blocks + 1) * prz->ecc_size;
if (ecc_total >= prz->buffer_size) {
pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
__func__, prz->ecc_size, ecc_total, prz->buffer_size);
return -EINVAL;
}
prz->buffer_size -= ecc_total;
prz->par_buffer = buffer->data + prz->buffer_size;
prz->par_header = prz->par_buffer + ecc_blocks * prz->ecc_size;
@ -397,7 +397,7 @@ static int __devinit persistent_ram_post_init(struct persistent_ram_zone *prz,
prz->ecc = ecc;
ret = persistent_ram_init_ecc(prz, prz->buffer_size);
ret = persistent_ram_init_ecc(prz);
if (ret)
return ret;