From e97bbe1b2bd82ec2ae37ad2e4965b4d3e78bbf7f Mon Sep 17 00:00:00 2001 From: Yichong Chen Date: Wed, 15 Jul 2026 13:20:06 +0800 Subject: [PATCH] ecryptfs: reject too-small tag 70 packets ecryptfs_parse_tag_70_packet() subtracts fixed metadata fields from the parsed packet body size to derive the encrypted filename size. A malformed packet with a body smaller than those fixed fields can underflow that size calculation. Reject tag 70 packets before the subtraction unless the body contains the signature, cipher code, and at least one byte of encrypted filename data. Fixes: 9c79f34f7ee7 ("eCryptfs: Filename Encryption: Tag 70 packets") Cc: Signed-off-by: Yichong Chen Signed-off-by: Tyler Hicks --- fs/ecryptfs/keystore.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c index 19bccba74c82..51651314b7a6 100644 --- a/fs/ecryptfs/keystore.c +++ b/fs/ecryptfs/keystore.c @@ -894,6 +894,12 @@ ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size, "rc = [%d]\n", __func__, rc); goto out; } + if (s->parsed_tag_70_packet_size < (ECRYPTFS_SIG_SIZE + 2)) { + ecryptfs_printk(KERN_WARNING, "Invalid packet size [%zd]\n", + s->parsed_tag_70_packet_size); + rc = -EINVAL; + goto out; + } s->block_aligned_filename_size = (s->parsed_tag_70_packet_size - ECRYPTFS_SIG_SIZE - 1); if ((1 + s->packet_size_len + s->parsed_tag_70_packet_size)