This is a note to let you know that I've just added the patch titled
crypto: scompress - Use per-CPU struct instead multiple variables
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
crypto-scompress-use-per-cpu-struct-instead-multiple.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit af67175aec67b7af42238066c2738e7e52340603
Author: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Date: Fri Mar 29 14:09:56 2019 +0100
crypto: scompress - Use per-CPU struct instead multiple variables
[ Upstream commit 71052dcf4be70be4077817297dcde7b155e745f2 ]
Two per-CPU variables are allocated as pointer to per-CPU memory which
then are used as scratch buffers.
We could be smart about this and use instead a per-CPU struct which
contains the pointers already and then we need to allocate just the
scratch buffers.
Add a lock to the struct. By doing so we can avoid the get_cpu()
statement and gain lockdep coverage (if enabled) to ensure that the lock
is always acquired in the right context. On non-preemptible kernels the
lock vanishes.
It is okay to use raw_cpu_ptr() in order to get a pointer to the struct
since it is protected by the spinlock.
The diffstat of this is negative and according to size scompress.o:
text data bss dec hex filename
1847 160 24 2031 7ef dbg_before.o
1754 232 4 1990 7c6 dbg_after.o
1799 64 24 1887 75f no_dbg-before.o
1703 88 4 1795 703 no_dbg-after.o
The overall size increase difference is also negative. The increase in
the data section is only four bytes without lockdep.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Stable-dep-of: 744e1885922a ("crypto: scomp - fix req->dst buffer overflow")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/crypto/scompress.c b/crypto/scompress.c
index 15641c96ff99..3702f1648ea8 100644
--- a/crypto/scompress.c
+++ b/crypto/scompress.c
@@ -29,9 +29,17 @@
#include <crypto/internal/scompress.h>
#include "internal.h"
+struct scomp_scratch {
+ spinlock_t lock;
+ void *src;
+ void *dst;
+};
+
+static DEFINE_PER_CPU(struct scomp_scratch, scomp_scratch) = {
+ .lock = __SPIN_LOCK_UNLOCKED(scomp_scratch.lock),
+};
+
static const struct crypto_type crypto_scomp_type;
-static void * __percpu *scomp_src_scratches;
-static void * __percpu *scomp_dst_scratches;
static int scomp_scratch_users;
static DEFINE_MUTEX(scomp_lock);
@@ -65,76 +73,53 @@ static void crypto_scomp_show(struct seq_file *m, struct crypto_alg *alg)
seq_puts(m, "type : scomp\n");
}
-static void crypto_scomp_free_scratches(void * __percpu *scratches)
+static void crypto_scomp_free_scratches(void)
{
+ struct scomp_scratch *scratch;
int i;
- if (!scratches)
- return;
-
- for_each_possible_cpu(i)
- vfree(*per_cpu_ptr(scratches, i));
+ for_each_possible_cpu(i) {
+ scratch = raw_cpu_ptr(&scomp_scratch);
- free_percpu(scratches);
+ vfree(scratch->src);
+ vfree(scratch->dst);
+ scratch->src = NULL;
+ scratch->dst = NULL;
+ }
}
-static void * __percpu *crypto_scomp_alloc_scratches(void)
+static int crypto_scomp_alloc_scratches(void)
{
- void * __percpu *scratches;
+ struct scomp_scratch *scratch;
int i;
- scratches = alloc_percpu(void *);
- if (!scratches)
- return NULL;
-
for_each_possible_cpu(i) {
- void *scratch;
-
- scratch = vmalloc_node(SCOMP_SCRATCH_SIZE, cpu_to_node(i));
- if (!scratch)
- goto error;
- *per_cpu_ptr(scratches, i) = scratch;
- }
-
- return scratches;
-
-error:
- crypto_scomp_free_scratches(scratches);
- return NULL;
-}
+ void *mem;
-static void crypto_scomp_free_all_scratches(void)
-{
- if (!--scomp_scratch_users) {
- crypto_scomp_free_scratches(scomp_src_scratches);
- crypto_scomp_free_scratches(scomp_dst_scratches);
- scomp_src_scratches = NULL;
- scomp_dst_scratches = NULL;
- }
-}
+ scratch = raw_cpu_ptr(&scomp_scratch);
-static int crypto_scomp_alloc_all_scratches(void)
-{
- if (!scomp_scratch_users++) {
- scomp_src_scratches = crypto_scomp_alloc_scratches();
- if (!scomp_src_scratches)
- return -ENOMEM;
- scomp_dst_scratches = crypto_scomp_alloc_scratches();
- if (!scomp_dst_scratches) {
- crypto_scomp_free_scratches(scomp_src_scratches);
- scomp_src_scratches = NULL;
- return -ENOMEM;
- }
+ mem = vmalloc_node(SCOMP_SCRATCH_SIZE, cpu_to_node(i));
+ if (!mem)
+ goto error;
+ scratch->src = mem;
+ mem = vmalloc_node(SCOMP_SCRATCH_SIZE, cpu_to_node(i));
+ if (!mem)
+ goto error;
+ scratch->dst = mem;
}
return 0;
+error:
+ crypto_scomp_free_scratches();
+ return -ENOMEM;
}
static int crypto_scomp_init_tfm(struct crypto_tfm *tfm)
{
- int ret;
+ int ret = 0;
mutex_lock(&scomp_lock);
- ret = crypto_scomp_alloc_all_scratches();
+ if (!scomp_scratch_users++)
+ ret = crypto_scomp_alloc_scratches();
mutex_unlock(&scomp_lock);
return ret;
@@ -146,31 +131,28 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
void **tfm_ctx = acomp_tfm_ctx(tfm);
struct crypto_scomp *scomp = *tfm_ctx;
void **ctx = acomp_request_ctx(req);
- const int cpu = get_cpu();
- u8 *scratch_src = *per_cpu_ptr(scomp_src_scratches, cpu);
- u8 *scratch_dst = *per_cpu_ptr(scomp_dst_scratches, cpu);
+ struct scomp_scratch *scratch;
int ret;
- if (!req->src || !req->slen || req->slen > SCOMP_SCRATCH_SIZE) {
- ret = -EINVAL;
- goto out;
- }
+ if (!req->src || !req->slen || req->slen > SCOMP_SCRATCH_SIZE)
+ return -EINVAL;
- if (req->dst && !req->dlen) {
- ret = -EINVAL;
- goto out;
- }
+ if (req->dst && !req->dlen)
+ return -EINVAL;
if (!req->dlen || req->dlen > SCOMP_SCRATCH_SIZE)
req->dlen = SCOMP_SCRATCH_SIZE;
- scatterwalk_map_and_copy(scratch_src, req->src, 0, req->slen, 0);
+ scratch = raw_cpu_ptr(&scomp_scratch);
+ spin_lock(&scratch->lock);
+
+ scatterwalk_map_and_copy(scratch->src, req->src, 0, req->slen, 0);
if (dir)
- ret = crypto_scomp_compress(scomp, scratch_src, req->slen,
- scratch_dst, &req->dlen, *ctx);
+ ret = crypto_scomp_compress(scomp, scratch->src, req->slen,
+ scratch->dst, &req->dlen, *ctx);
else
- ret = crypto_scomp_decompress(scomp, scratch_src, req->slen,
- scratch_dst, &req->dlen, *ctx);
+ ret = crypto_scomp_decompress(scomp, scratch->src, req->slen,
+ scratch->dst, &req->dlen, *ctx);
if (!ret) {
if (!req->dst) {
req->dst = sgl_alloc(req->dlen, GFP_ATOMIC, NULL);
@@ -179,11 +161,11 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
goto out;
}
}
- scatterwalk_map_and_copy(scratch_dst, req->dst, 0, req->dlen,
+ scatterwalk_map_and_copy(scratch->dst, req->dst, 0, req->dlen,
1);
}
out:
- put_cpu();
+ spin_unlock(&scratch->lock);
return ret;
}
@@ -204,7 +186,8 @@ static void crypto_exit_scomp_ops_async(struct crypto_tfm *tfm)
crypto_free_scomp(*ctx);
mutex_lock(&scomp_lock);
- crypto_scomp_free_all_scratches();
+ if (!--scomp_scratch_users)
+ crypto_scomp_free_scratches();
mutex_unlock(&scomp_lock);
}
