From: Sabyrzhan Tasbolatov snovitoll@gmail.com
commit 7ef4c19d245f3dc233fd4be5acea436edd1d83d8 upstream.
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 than PAGE_SIZE.
Per smackfs doc, smk_write_net4addr accepts any label or -CIPSO, smk_write_net6addr accepts any label or -DELETE. I couldn't find any general rule for other label lengths except SMK_LABELLEN, SMK_LONGLABEL, SMK_CIPSOMAX which are documented.
Let's constrain, in general, smackfs label lengths for PAGE_SIZE. Although fuzzer crashes write to smackfs/netlabel on 0x400000 length.
Here is a quick way to reproduce the WARNING: python -c "print('A' * 0x400000)" > /sys/fs/smackfs/netlabel
Reported-by: syzbot+a71a442385a0b2815497@syzkaller.appspotmail.com Signed-off-by: Sabyrzhan Tasbolatov snovitoll@gmail.com Signed-off-by: Casey Schaufler casey@schaufler-ca.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- security/smack/smackfs.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-)
--- a/security/smack/smackfs.c +++ b/security/smack/smackfs.c @@ -1163,7 +1163,7 @@ static ssize_t smk_write_net4addr(struct return -EPERM; if (*ppos != 0) return -EINVAL; - if (count < SMK_NETLBLADDRMIN) + if (count < SMK_NETLBLADDRMIN || count > PAGE_SIZE - 1) return -EINVAL;
data = memdup_user_nul(buf, count); @@ -1423,7 +1423,7 @@ static ssize_t smk_write_net6addr(struct return -EPERM; if (*ppos != 0) return -EINVAL; - if (count < SMK_NETLBLADDRMIN) + if (count < SMK_NETLBLADDRMIN || count > PAGE_SIZE - 1) return -EINVAL;
data = memdup_user_nul(buf, count); @@ -1830,6 +1830,10 @@ static ssize_t smk_write_ambient(struct if (!smack_privileged(CAP_MAC_ADMIN)) return -EPERM;
+ /* Enough data must be present */ + if (count == 0 || count > PAGE_SIZE) + return -EINVAL; + data = memdup_user_nul(buf, count); if (IS_ERR(data)) return PTR_ERR(data); @@ -2001,6 +2005,9 @@ static ssize_t smk_write_onlycap(struct if (!smack_privileged(CAP_MAC_ADMIN)) return -EPERM;
+ if (count > PAGE_SIZE) + return -EINVAL; + data = memdup_user_nul(buf, count); if (IS_ERR(data)) return PTR_ERR(data); @@ -2088,6 +2095,9 @@ static ssize_t smk_write_unconfined(stru if (!smack_privileged(CAP_MAC_ADMIN)) return -EPERM;
+ if (count > PAGE_SIZE) + return -EINVAL; + data = memdup_user_nul(buf, count); if (IS_ERR(data)) return PTR_ERR(data); @@ -2643,6 +2653,10 @@ static ssize_t smk_write_syslog(struct f if (!smack_privileged(CAP_MAC_ADMIN)) return -EPERM;
+ /* Enough data must be present */ + if (count == 0 || count > PAGE_SIZE) + return -EINVAL; + data = memdup_user_nul(buf, count); if (IS_ERR(data)) return PTR_ERR(data); @@ -2735,10 +2749,13 @@ static ssize_t smk_write_relabel_self(st return -EPERM;
/* + * No partial write. * Enough data must be present. */ if (*ppos != 0) return -EINVAL; + if (count == 0 || count > PAGE_SIZE) + return -EINVAL;
data = memdup_user_nul(buf, count); if (IS_ERR(data))