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Subject[PATCH 4.19 101/105] pstore: Refactor compression initialization
Date
From: Kees Cook <keescook@chromium.org>

commit 95047b0519c17a28e09df5f38750f5354e3db4c4 upstream.

This refactors compression initialization slightly to better handle
getting potentially called twice (via early pstore_register() calls
and later pstore_init()) and improves the comments and reporting to be
more verbose.

Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/pstore/platform.c | 48 +++++++++++++++++++++++++++++++++---------------
1 file changed, 33 insertions(+), 15 deletions(-)

--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -274,36 +274,56 @@ static int pstore_decompress(void *in, v

static void allocate_buf_for_compression(void)
{
+ struct crypto_comp *ctx;
+ int size;
+ char *buf;
+
+ /* Skip if not built-in or compression backend not selected yet. */
if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
return;

+ /* Skip if no pstore backend yet or compression init already done. */
+ if (!psinfo || tfm)
+ return;
+
if (!crypto_has_comp(zbackend->name, 0, 0)) {
- pr_err("No %s compression\n", zbackend->name);
+ pr_err("Unknown compression: %s\n", zbackend->name);
return;
}

- big_oops_buf_sz = zbackend->zbufsize(psinfo->bufsize);
- if (big_oops_buf_sz <= 0)
+ size = zbackend->zbufsize(psinfo->bufsize);
+ if (size <= 0) {
+ pr_err("Invalid compression size for %s: %d\n",
+ zbackend->name, size);
return;
+ }

- big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
- if (!big_oops_buf) {
- pr_err("allocate compression buffer error!\n");
+ buf = kmalloc(size, GFP_KERNEL);
+ if (!buf) {
+ pr_err("Failed %d byte compression buffer allocation for: %s\n",
+ size, zbackend->name);
return;
}

- tfm = crypto_alloc_comp(zbackend->name, 0, 0);
- if (IS_ERR_OR_NULL(tfm)) {
- kfree(big_oops_buf);
- big_oops_buf = NULL;
- pr_err("crypto_alloc_comp() failed!\n");
+ ctx = crypto_alloc_comp(zbackend->name, 0, 0);
+ if (IS_ERR_OR_NULL(ctx)) {
+ kfree(buf);
+ pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
+ PTR_ERR(ctx));
return;
}
+
+ /* A non-NULL big_oops_buf indicates compression is available. */
+ tfm = ctx;
+ big_oops_buf_sz = size;
+ big_oops_buf = buf;
+
+ pr_info("Using compression: %s\n", zbackend->name);
}

static void free_buf_for_compression(void)
{
- if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && !IS_ERR_OR_NULL(tfm))
+ if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm)
crypto_free_comp(tfm);
kfree(big_oops_buf);
big_oops_buf = NULL;
@@ -774,7 +794,6 @@ void __init pstore_choose_compression(vo
for (step = zbackends; step->name; step++) {
if (!strcmp(compress, step->name)) {
zbackend = step;
- pr_info("using %s compression\n", zbackend->name);
return;
}
}
@@ -791,8 +810,7 @@ static int __init pstore_init(void)
* initialize compression because crypto was not ready. If so,
* initialize compression now.
*/
- if (psinfo && !tfm)
- allocate_buf_for_compression();
+ allocate_buf_for_compression();

ret = pstore_init_fs();
if (ret)

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