Date: Sat, 10 Apr 2021 22:05:22 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 254964] Integer overflow in ffs_setextattr() could lead to a kernel heap overflow Message-ID: <bug-254964-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D254964 Bug ID: 254964 Summary: Integer overflow in ffs_setextattr() could lead to a kernel heap overflow Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Many People Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: cutesmilee.research@protonmail.com ffs_setextattr() is used to set a named attribute to an ffs vfs. the problem is that it takes some user controlled data, the interesting ones are: ap->a_name (arbitrary user string, not checked), and ip->i_ea_len (unsigned int), which also isn't checked. the function uses ip->i_ea_len + ealength (which is 7 + strlen(ap->a_name))= for allocating a buffer, after that user-controlled data are copied to the buff= er using ip->i_ea_len. providing an INT_MAX ip->i_ea_len + 2^32 + 2 long string will cause an inte= ger overflow, and the buffer in the heap will be 1 byte, but the bcopy will copy 2^32 bytes to the buffer. this should be reachable from an unprivileged user (since extattr_check_cre= d() doesn't require root if the attrnamespace is set to EXTATTR_NAMESPACE_USER), but seems to be difficult to exploit, since you'd need 4GBs of ram (for the long string) just to perform the 2^32 heap overflow, an exploitable overflow will probably take even more memory. --=20 You are receiving this mail because: You are the assignee for the bug.=
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