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

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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: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2018-03-07 12:18:33 -08:00
parent fe1d475888
commit f2531f1976
2 changed files with 23 additions and 7 deletions
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29
fs/pstore/ram_core.c
View file

@ -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);
}

1
include/linux/pstore_ram.h
View file

@ -39,6 +39,7 @@ struct persistent_ram_ecc_info {
int ecc_size;
int symsize;
int poly;
uint16_t *par;
};
struct persistent_ram_zone {