[PATCH] smackfs: restrict bytes count in smackfs write functions
From: Sabyrzhan Tasbolatov <hidden>
Date: 2021-01-24 14:37:30
Also in:
lkml
Subsystem:
security subsystem, smack security module, the rest · Maintainers:
Paul Moore, James Morris, "Serge E. Hallyn", Casey Schaufler, Linus Torvalds
syzbot found WARNINGs in several smackfs write operations where bytes count is passed to memdup_user_nul which exceeds GFP MAX_ORDER. Check count size if bigger SMK_LONGLABEL, for smk_write_syslog if bigger than PAGE_SIZE - 1. Reported-by: syzbot+a71a442385a0b2815497@syzkaller.appspotmail.com Signed-off-by: Sabyrzhan Tasbolatov <redacted> --- security/smack/smackfs.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 5d44b7d258ef..88678c6f1b8c 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c@@ -1167,7 +1167,7 @@ static ssize_t smk_write_net4addr(struct file *file, const char __user *buf, return -EPERM; if (*ppos != 0) return -EINVAL; - if (count < SMK_NETLBLADDRMIN) + if (count < SMK_NETLBLADDRMIN || count > SMK_LONGLABEL) return -EINVAL; data = memdup_user_nul(buf, count);
@@ -1427,7 +1427,7 @@ static ssize_t smk_write_net6addr(struct file *file, const char __user *buf, return -EPERM; if (*ppos != 0) return -EINVAL; - if (count < SMK_NETLBLADDRMIN) + if (count < SMK_NETLBLADDRMIN || count > SMK_LONGLABEL) return -EINVAL; data = memdup_user_nul(buf, count);
@@ -2647,6 +2647,8 @@ static ssize_t smk_write_syslog(struct file *file, const char __user *buf, if (!smack_privileged(CAP_MAC_ADMIN)) return -EPERM; + if (count > PAGE_SIZE - 1) + return -EINVAL; data = memdup_user_nul(buf, count); if (IS_ERR(data))
@@ -2744,6 +2746,8 @@ static ssize_t smk_write_relabel_self(struct file *file, const char __user *buf, */ if (*ppos != 0) return -EINVAL; + if (count > SMK_LONGLABEL) + return -EINVAL; data = memdup_user_nul(buf, count); if (IS_ERR(data))
--
2.25.1