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Commit f2531f19 authored by Kees Cook's avatar Kees Cook
Browse files

pstore/ram: Do not use stack VLA for parity workspace 



Instead of using a stack VLA for the parity workspace, preallocate a
memory region. The preallocation is done to keep from needing to perform
allocations during crash dump writing, etc. This also fixes a missed
release of librs on free.

Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent fe1d4758

fs/pstore/ram_core.c

+22 −7
Original line number Diff line number Diff line
@@ -98,24 +98,23 @@ static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz, 
	uint8_t *data, size_t len, uint8_t *ecc)

{

	int i;

	uint16_t par[prz->ecc_info.ecc_size];



	/* Initialize the parity buffer */

	memset(par, 0, sizeof(par));

	encode_rs8(prz->rs_decoder, data, len, par, 0);

	memset(prz->ecc_info.par, 0,

	       prz->ecc_info.ecc_size * sizeof(prz->ecc_info.par[0]));

	encode_rs8(prz->rs_decoder, data, len, prz->ecc_info.par, 0);

	for (i = 0; i < prz->ecc_info.ecc_size; i++)

		ecc[i] = par[i];

		ecc[i] = prz->ecc_info.par[i];

}



static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,

	void *data, size_t len, uint8_t *ecc)

{

	int i;

	uint16_t par[prz->ecc_info.ecc_size];



	for (i = 0; i < prz->ecc_info.ecc_size; i++)

		par[i] = ecc[i];

	return decode_rs8(prz->rs_decoder, data, par, len,

		prz->ecc_info.par[i] = ecc[i];

	return decode_rs8(prz->rs_decoder, data, prz->ecc_info.par, len,

				NULL, 0, NULL, 0, NULL);

}
@@ -228,6 +227,15 @@ static int persistent_ram_init_ecc(struct persistent_ram_zone *prz, 
		return -EINVAL;

	}



	/* allocate workspace instead of using stack VLA */

	prz->ecc_info.par = kmalloc_array(prz->ecc_info.ecc_size,

					  sizeof(*prz->ecc_info.par),

					  GFP_KERNEL);

	if (!prz->ecc_info.par) {

		pr_err("cannot allocate ECC parity workspace\n");

		return -ENOMEM;

	}



	prz->corrected_bytes = 0;

	prz->bad_blocks = 0;
@@ -514,6 +522,13 @@ void persistent_ram_free(struct persistent_ram_zone *prz) 
		}

		prz->vaddr = NULL;

	}

	if (prz->rs_decoder) {

		free_rs(prz->rs_decoder);

		prz->rs_decoder = NULL;

	}

	kfree(prz->ecc_info.par);

	prz->ecc_info.par = NULL;



	persistent_ram_free_old(prz);

	kfree(prz);

}

include/linux/pstore_ram.h

+1 −0
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ struct persistent_ram_ecc_info { 
	int ecc_size;

	int symsize;

	int poly;

	uint16_t *par;

};



struct persistent_ram_zone {