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From: "bugdal at aerifal dot cx" <sourceware-bugzilla@sourceware.org> To: glibc-bugs@sources.redhat.com Subject: [Bug nptl/13347] New: Threaded setuid() can wrongly report success when failing to drop privileges Date: Wed, 26 Oct 2011 03:33:00 -0000 [thread overview] Message-ID: <bug-13347-131@http.sourceware.org/bugzilla/> (raw) http://sourceware.org/bugzilla/show_bug.cgi?id=13347 Bug #: 13347 Summary: Threaded setuid() can wrongly report success when failing to drop privileges Product: glibc Version: unspecified Status: NEW Severity: normal Priority: P2 Component: nptl AssignedTo: drepper.fsp@gmail.com ReportedBy: bugdal@aerifal.cx Classification: Unclassified Created attachment 6035 --> http://sourceware.org/bugzilla/attachment.cgi?id=6035 Test case that demonstrates the race on pre-3.1 kernels The "setxid" system by which glibc/nptl synchronizes uid/gid changes using signals fails to check the return value of the system call in any thread but the original caller. Thus, it is possible for some threads to retain their original uid (e.g. root) permanently after setuid(somebody) returns success. The main cause of failure of setuid at the kernel level is exceeding RLIMIT_NPROC, and as far as I know, this failure case has finally been removed in Linux 3.1. However, it's possible that other temporary resource exhaustion issues could cause setuid to intermittently fail even on newer kernels. See the attached test case for a demonstration of the bug that works on pre-3.1 kernels. It might be necessary to adjust the timing to hit the race, but on my machines it usually hits the race within the first 1-5 iterations. Note that I am not issuing an advisory or elevating the severity because there seems to be little or no real-world code that depends on multithreaded setuid(). Nonetheless, this is a security bug and should be treated seriously. -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
next reply other threads:[~2011-10-26 3:33 UTC|newest] Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-10-26 3:33 bugdal at aerifal dot cx [this message] 2012-03-17 20:38 ` [Bug nptl/13347] " bugdal at aerifal dot cx 2012-04-29 3:03 ` bugdal at aerifal dot cx 2012-04-29 17:00 ` ppluzhnikov at google dot com 2012-07-24 14:52 ` carlos_odonell at mentor dot com 2012-07-24 14:56 ` fweimer at redhat dot com 2012-07-24 18:15 ` bugdal at aerifal dot cx 2012-07-24 18:35 ` carlos_odonell at mentor dot com 2012-07-24 23:04 ` bugdal at aerifal dot cx 2012-07-25 2:20 ` carlos_odonell at mentor dot com 2012-12-03 23:57 ` carlos at systemhalted dot org 2014-03-24 13:57 ` fweimer at redhat dot com 2014-03-24 15:19 ` bugdal at aerifal dot cx 2014-03-24 18:32 ` carlos at redhat dot com 2014-04-01 10:13 ` cvs-commit at gcc dot gnu.org 2014-04-01 11:54 ` joseph at codesourcery dot com 2014-04-01 12:21 ` fweimer at redhat dot com 2014-04-01 12:21 ` cvs-commit at gcc dot gnu.org 2014-06-27 11:43 ` fweimer at redhat dot com 2014-06-27 13:15 ` bugdal at aerifal dot cx 2014-07-09 10:26 ` fweimer at redhat dot com 2014-07-22 12:35 ` fweimer at redhat dot com 2014-07-22 12:57 ` bugdal at aerifal dot cx
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