| Message ID | 20200723152219.GA302005@mwanda (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] Smack: fix another vsscanf out of bounds | expand |
On 7/23/2020 8:22 AM, Dan Carpenter wrote: > This is similar to commit 84e99e58e8d1 ("Smack: slab-out-of-bounds in > vsscanf") where we added a bounds check on "rule". > > Reported-by: syzbot+a22c6092d003d6fe1122@syzkaller.appspotmail.com > Fixes: f7112e6c9abf ("Smack: allow for significantly longer Smack labels v4") > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Thanks. I'll be testing these and take them assuming they pass. > --- > This check is very straight forward and should fix the bug. But if you > look at the fixes tag we used to rely on the check: > > if (count != (SMK_CIPSOMIN + catlen * SMK_DIGITLEN)) > > and now that has been changed to: > > if (format == SMK_FIXED24_FMT && > count != (SMK_CIPSOMIN + catlen * SMK_DIGITLEN)) > goto out; > > so it doesn't apply for every format. > > security/smack/smackfs.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c > index c21b656b3263..81c6ceeaa4f9 100644 > --- a/security/smack/smackfs.c > +++ b/security/smack/smackfs.c > @@ -905,6 +905,10 @@ static ssize_t smk_set_cipso(struct file *file, const char __user *buf, > > for (i = 0; i < catlen; i++) { > rule += SMK_DIGITLEN; > + if (rule > data + count) { > + rc = -EOVERFLOW; > + goto out; > + } > ret = sscanf(rule, "%u", &cat); > if (ret != 1 || cat > SMACK_CIPSO_MAXCATNUM) > goto out;
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c index c21b656b3263..81c6ceeaa4f9 100644 --- a/security/smack/smackfs.c +++ b/security/smack/smackfs.c @@ -905,6 +905,10 @@ static ssize_t smk_set_cipso(struct file *file, const char __user *buf, for (i = 0; i < catlen; i++) { rule += SMK_DIGITLEN; + if (rule > data + count) { + rc = -EOVERFLOW; + goto out; + } ret = sscanf(rule, "%u", &cat); if (ret != 1 || cat > SMACK_CIPSO_MAXCATNUM) goto out;
This is similar to commit 84e99e58e8d1 ("Smack: slab-out-of-bounds in vsscanf") where we added a bounds check on "rule". Reported-by: syzbot+a22c6092d003d6fe1122@syzkaller.appspotmail.com Fixes: f7112e6c9abf ("Smack: allow for significantly longer Smack labels v4") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> --- This check is very straight forward and should fix the bug. But if you look at the fixes tag we used to rely on the check: if (count != (SMK_CIPSOMIN + catlen * SMK_DIGITLEN)) and now that has been changed to: if (format == SMK_FIXED24_FMT && count != (SMK_CIPSOMIN + catlen * SMK_DIGITLEN)) goto out; so it doesn't apply for every format. security/smack/smackfs.c | 4 ++++ 1 file changed, 4 insertions(+)