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authorIgor Zhbanov <i.zhbanov@samsung.com>2013-03-19 13:49:47 +0400
committerCasey Schaufler <casey@schaufler-ca.com>2013-03-19 14:38:17 -0700
commitcdb56b60884c687ea396ae96a418554739b40129 (patch)
tree325dc2701fd0a5d5356b48ad1f032badbbe6dd75 /security/smack
parente05b6f982a049113a88a1750e13fdb15298cbed4 (diff)
downloadlinux-stericsson-cdb56b60884c687ea396ae96a418554739b40129.tar.gz
Fix NULL pointer dereference in smack_inode_unlink() and smack_inode_rmdir()
This patch fixes kernel Oops because of wrong common_audit_data type in smack_inode_unlink() and smack_inode_rmdir(). When SMACK security module is enabled and SMACK logging is on (/smack/logging is not zero) and you try to delete the file which 1) you cannot delete due to SMACK rules and logging of failures is on or 2) you can delete and logging of success is on, you will see following: Unable to handle kernel NULL pointer dereference at virtual address 000002d7 [<...>] (strlen+0x0/0x28) [<...>] (audit_log_untrustedstring+0x14/0x28) [<...>] (common_lsm_audit+0x108/0x6ac) [<...>] (smack_log+0xc4/0xe4) [<...>] (smk_curacc+0x80/0x10c) [<...>] (smack_inode_unlink+0x74/0x80) [<...>] (security_inode_unlink+0x2c/0x30) [<...>] (vfs_unlink+0x7c/0x100) [<...>] (do_unlinkat+0x144/0x16c) The function smack_inode_unlink() (and smack_inode_rmdir()) need to log two structures of different types. First of all it does: smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_DENTRY); smk_ad_setfield_u_fs_path_dentry(&ad, dentry); This will set common audit data type to LSM_AUDIT_DATA_DENTRY and store dentry for auditing (by function smk_curacc(), which in turn calls dump_common_audit_data(), which is actually uses provided data and logs it). /* * You need write access to the thing you're unlinking */ rc = smk_curacc(smk_of_inode(ip), MAY_WRITE, &ad); if (rc == 0) { /* * You also need write access to the containing directory */ Then this function wants to log anoter data: smk_ad_setfield_u_fs_path_dentry(&ad, NULL); smk_ad_setfield_u_fs_inode(&ad, dir); The function sets inode field, but don't change common_audit_data type. rc = smk_curacc(smk_of_inode(dir), MAY_WRITE, &ad); } So the dump_common_audit() function incorrectly interprets inode structure as dentry, and Oops will happen. This patch reinitializes common_audit_data structures with correct type. Also I removed unneeded smk_ad_setfield_u_fs_path_dentry(&ad, NULL); initialization, because both dentry and inode pointers are stored in the same union. Signed-off-by: Igor Zhbanov <i.zhbanov@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Diffstat (limited to 'security/smack')
-rw-r--r--security/smack/smack_lsm.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index fa64740abb59..d52c780bdb78 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -654,7 +654,7 @@ static int smack_inode_unlink(struct inode *dir, struct dentry *dentry)
/*
* You also need write access to the containing directory
*/
- smk_ad_setfield_u_fs_path_dentry(&ad, NULL);
+ smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_INODE);
smk_ad_setfield_u_fs_inode(&ad, dir);
rc = smk_curacc(smk_of_inode(dir), MAY_WRITE, &ad);
}
@@ -685,7 +685,7 @@ static int smack_inode_rmdir(struct inode *dir, struct dentry *dentry)
/*
* You also need write access to the containing directory
*/
- smk_ad_setfield_u_fs_path_dentry(&ad, NULL);
+ smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_INODE);
smk_ad_setfield_u_fs_inode(&ad, dir);
rc = smk_curacc(smk_of_inode(dir), MAY_WRITE, &ad);
}