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authorJoel Fernandes (Google) <joel@joelfernandes.org>2018-11-03 16:38:18 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-01-26 09:37:02 +0100
commite1e3a46706bd4037e8b7407dc660ae6e05b8ac56 (patch)
tree48905eb06e03f5fdd6abfed3515fb473b56e1bc1
parentbf34ede3a11d58e3bcf7007bf14f6a94562bc8f1 (diff)
download96b-common-e1e3a46706bd4037e8b7407dc660ae6e05b8ac56.tar.gz
pstore/ram: Do not treat empty buffers as valid
[ Upstream commit 30696378f68a9e3dad6bfe55938b112e72af00c2 ] The ramoops backend currently calls persistent_ram_save_old() even if a buffer is empty. While this appears to work, it is does not seem like the right thing to do and could lead to future bugs so lets avoid that. It also prevents misleading prints in the logs which claim the buffer is valid. I got something like: found existing buffer, size 0, start 0 When I was expecting: no valid data in buffer (sig = ...) This bails out early (and reports with pr_debug()), since it's an acceptable state. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Co-developed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r--fs/pstore/ram_core.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index ecdb3baa1283..11e558efd61e 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -488,6 +488,11 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
sig ^= PERSISTENT_RAM_SIG;
if (prz->buffer->sig == sig) {
+ if (buffer_size(prz) == 0) {
+ pr_debug("found existing empty buffer\n");
+ return 0;
+ }
+
if (buffer_size(prz) > prz->buffer_size ||
buffer_start(prz) > buffer_size(prz))
pr_info("found existing invalid buffer, size %zu, start %zu\n",