From 2602b79c5b3e2f6fce12e38a670f8e3fda4e46a2 Mon Sep 17 00:00:00 2001 From: Yichong Chen Date: Wed, 15 Jul 2026 13:20:04 +0800 Subject: [PATCH] ecryptfs: pass packet set buffer size to parser ecryptfs_parse_packet_set() receives a pointer into the file header, but it calculates the remaining packet buffer size from PAGE_SIZE - 8. For version 1 headers the packet set starts later in the header, so this can overstate the available buffer. Pass the actual packet set buffer length from the caller and calculate per-packet limits from the remaining bytes in that buffer. Recompute the remaining length after consuming a tag 3 packet before parsing the following tag 11 packet. Fixes: 237fead61998 ("[PATCH] ecryptfs: fs/Makefile and fs/Kconfig") Cc: Signed-off-by: Yichong Chen Signed-off-by: Tyler Hicks --- fs/ecryptfs/crypto.c | 2 +- fs/ecryptfs/ecryptfs_kernel.h | 3 ++- fs/ecryptfs/keystore.c | 23 ++++++++++++++++++++--- 3 files changed, 23 insertions(+), 5 deletions(-) diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c index 74b02b55e3f6..e67119b6029c 100644 --- a/fs/ecryptfs/crypto.c +++ b/fs/ecryptfs/crypto.c @@ -1197,7 +1197,7 @@ static int ecryptfs_read_headers_virt(char *page_virt, } else set_default_header_data(crypt_stat); rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset), - ecryptfs_dentry); + PAGE_SIZE - offset, ecryptfs_dentry); out: return rc; } diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h index f4f56a92bd56..7d2488a10b17 100644 --- a/fs/ecryptfs/ecryptfs_kernel.h +++ b/fs/ecryptfs/ecryptfs_kernel.h @@ -580,7 +580,8 @@ int ecryptfs_generate_key_packet_set(char *dest_base, size_t *len, size_t max); int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat, - unsigned char *src, struct dentry *ecryptfs_dentry); + unsigned char *src, size_t src_size, + struct dentry *ecryptfs_dentry); int ecryptfs_truncate(struct dentry *dentry, loff_t new_length); ssize_t ecryptfs_getxattr_lower(struct dentry *lower_dentry, struct inode *lower_inode, diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c index e200ab0eba16..6402c0cdb7f4 100644 --- a/fs/ecryptfs/keystore.c +++ b/fs/ecryptfs/keystore.c @@ -1714,6 +1714,7 @@ decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok, * ecryptfs_parse_packet_set * @crypt_stat: The cryptographic context * @src: Virtual address of region of memory containing the packets + * @src_size: Size of the packet set buffer * @ecryptfs_dentry: The eCryptfs dentry associated with the packet set * * Get crypt_stat to have the file's session key if the requisite key @@ -1724,7 +1725,7 @@ decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok, * conditions. */ int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat, - unsigned char *src, + unsigned char *src, size_t src_size, struct dentry *ecryptfs_dentry) { size_t i = 0; @@ -1746,7 +1747,11 @@ int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat, * added the our &auth_tok_list */ next_packet_is_auth_tok_packet = 1; while (next_packet_is_auth_tok_packet) { - size_t max_packet_size = ((PAGE_SIZE - 8) - i); + size_t max_packet_size; + + if (i >= src_size) + break; + max_packet_size = src_size - i; switch (src[i]) { case ECRYPTFS_TAG_3_PACKET_TYPE: @@ -1761,12 +1766,16 @@ int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat, goto out_wipe_list; } i += packet_size; + if (i > src_size) { + rc = -EIO; + goto out_wipe_list; + } rc = parse_tag_11_packet((unsigned char *)&src[i], sig_tmp_space, ECRYPTFS_SIG_SIZE, &tag_11_contents_size, &tag_11_packet_size, - max_packet_size); + src_size - i); if (rc) { ecryptfs_printk(KERN_ERR, "No valid " "(ecryptfs-specific) literal " @@ -1778,6 +1787,10 @@ int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat, goto out_wipe_list; } i += tag_11_packet_size; + if (i > src_size) { + rc = -EIO; + goto out_wipe_list; + } if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) { ecryptfs_printk(KERN_ERR, "Expected " "signature of size [%d]; " @@ -1803,6 +1816,10 @@ int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat, goto out_wipe_list; } i += packet_size; + if (i > src_size) { + rc = -EIO; + goto out_wipe_list; + } crypt_stat->flags |= ECRYPTFS_ENCRYPTED; break; case ECRYPTFS_TAG_11_PACKET_TYPE: