| Message ID | 20210124143627.582115-1-snovitoll@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | smackfs: restrict bytes count in smackfs write functions | expand |
On 1/24/2021 6:36 AM, Sabyrzhan Tasbolatov wrote: > 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 <snovitoll@gmail.com> Thank you for the patch. Unfortunately, SMK_LONGLABEL isn't the right value in some of these cases. > --- > 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))
On 2021/01/26 3:08, Casey Schaufler wrote: > On 1/24/2021 6:36 AM, Sabyrzhan Tasbolatov wrote: >> 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 <snovitoll@gmail.com> > > Thank you for the patch. Unfortunately, SMK_LONGLABEL isn't > the right value in some of these cases. > Since it uses sscanf(), I think that whitespaces must be excluded from upper limit check. I'm proposing adding __GFP_NOWARM on the memdup_user_nul() side at https://lkml.kernel.org/r/20210120103436.11830-1-penguin-kernel@I-love.SAKURA.ne.jp .
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))
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 <snovitoll@gmail.com> --- security/smack/smackfs.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)