Commit 1e6a9e56 authored by Anton Vorontsov's avatar Anton Vorontsov Committed by Greg Kroah-Hartman
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pstore/ram_core: Better ECC size checking 



- 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: default avatarAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent beeb9432

fs/pstore/ram_core.c

+8 −8
Original line number Diff line number Diff line
@@ -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;