When doing the 4.9 merge into certain Android trees, I noticed a warning from Android's deprecated GCC 4.9.4, which causes a build failure in those trees due to basically -Werror:

fs/ecryptfs/keystore.c: In function 'ecryptfs_parse_packet_set': fs/ecryptfs/keystore.c:1357:2: warning: 'auth_tok_list_item' may be used uninitialized in this function [-Wmaybe-uninitialized] memset(auth_tok_list_item, 0, ^ fs/ecryptfs/keystore.c:1260:38: note: 'auth_tok_list_item' was declared here struct ecryptfs_auth_tok_list_item *auth_tok_list_item; ^

GCC 9.2.0 was not able to pick up this warning when I tested it.

Turns out that Clang warns as well when -Wuninitialized is used, which is not the case in older stable trees at the moment (but shows value in potentially backporting the various warning fixes currently in upstream to get more coverage).

fs/ecryptfs/keystore.c:1284:6: warning: variable 'auth_tok_list_item' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ fs/ecryptfs/keystore.c:1360:4: note: uninitialized use occurs here auth_tok_list_item); ^~~~~~~~~~~~~~~~~~ fs/ecryptfs/keystore.c:1284:2: note: remove the 'if' if its condition is always false if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ fs/ecryptfs/keystore.c:1260:56: note: initialize the variable 'auth_tok_list_item' to silence this warning struct ecryptfs_auth_tok_list_item *auth_tok_list_item; ^ = NULL 1 warning generated.

Somehow, commit fe2e082f5da5 ("ecryptfs: fix a memory leak bug in parse_tag_1_packet()") upstream was not applied in the correct if block in 4.4.215, 4.9.215, and 4.14.172, which will indeed lead to use of uninitialized memory. Fix it up by undoing the bad backport in those trees then reapplying the patch in the proper location.

Signed-off-by: Nathan Chancellor natechancellor@gmail.com --- fs/ecryptfs/keystore.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c index 3f3ec50bf773..b134315fb69d 100644 --- a/fs/ecryptfs/keystore.c +++ b/fs/ecryptfs/keystore.c @@ -1285,7 +1285,7 @@ parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat, printk(KERN_ERR "Enter w/ first byte != 0x%.2x\n", ECRYPTFS_TAG_1_PACKET_TYPE); rc = -EINVAL; - goto out_free; + goto out; } /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or * at end of function upon failure */ @@ -1335,7 +1335,7 @@ parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat, printk(KERN_WARNING "Tag 1 packet contains key larger " "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES"); rc = -EINVAL; - goto out; + goto out_free; } memcpy((*new_auth_tok)->session_key.encrypted_key, &data[(*packet_size)], (body_size - (ECRYPTFS_SIG_SIZE + 2)));