Date: Sun, 24 Jan 2016 00:13:59 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 206551] Integer overflow in iconv kernel module Message-ID: <bug-206551-8@https.bugs.freebsd.org/bugzilla/>
next in thread | raw e-mail | index | archive | help
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D206551 Bug ID: 206551 Summary: Integer overflow in iconv kernel module Product: Base System Version: 11.0-CURRENT Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: freebsd-bugs@FreeBSD.org Reporter: ertl.chris@gmail.com After loading the iconv kernel module, a new sysctl name, "kern.iconv.add" = is accessible for `root` user. This is handled with the following code: static int iconv_sysctl_add(SYSCTL_HANDLER_ARGS) { ... if (din.ia_datalen > ICONV_CSMAXDATALEN) return EINVAL; ... if (din.ia_datalen) { csp->cp_data =3D malloc(din.ia_datalen, M_ICONVDATA, M_WAITOK); error =3D copyin(din.ia_data, csp->cp_data, din.ia_datalen); if (error) goto bad; } ... } Since the `ia_datalen` member of `struct iconv_add_in` is signed: struct iconv_add_in { int ia_version; char ia_converter[ICONV_CNVNMAXLEN]; char ia_to[ICONV_CSNMAXLEN]; char ia_from[ICONV_CSNMAXLEN]; int ia_datalen; const void *ia_data; }; The check on user supplied `din.ia_datalen` is insufficient. If a negative value is passed, it will bypass the check, and then wraparound to a huge va= lue when converted to an `unsigned` type to be passed to `malloc` and `copyin`.= For example, passing `-1` will bypass the check, and then attempt to allocate a= nd copy to a buffer of size `0xffffffff`. The impact of this is low, since it is only triggerable as `root`, and coul= d at most result in DoS. The solution is to replace this check: if (din.ia_datalen > ICONV_CSMAXDATALEN) With this: if (din.ia_datalen > ICONV_CSMAXDATALEN || din.ia_datalen < 0) --=20 You are receiving this mail because: You are the assignee for the bug.=
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?bug-206551-8>