Date: Tue, 28 Feb 2023 19:55:43 -0600 From: John Helmert III <ajak@...too.org> To: oss-security@...ts.openwall.com Subject: Re: sudo: double free with per-command chroot sudoers rules Has a CVE been requeested? On Tue, Feb 28, 2023 at 07:31:11AM -0700, Todd C. Miller wrote: > A flaw exists in sudo's per-command chroot feature that could result > in the variable that stores the command being freed more than once. > > I believe this is a fairly low-impact bug as the per-command chroot > feature is not widely used. The bug was caught by glibc's double-free > detection while I was performing some chroot-related testing. No > one else has reported the bug which leads me to believe it probably > has not been encountered in the wild. > > Sudo versions affected: > > Sudo versions 1.9.8 through 1.9.13p1 inclusive are affected. > Versions of sudo prior to 1.9.8 are not affected. > > Details: > > Starting with Sudo 1.9.3, it is possible to specify an alternate > root directory that sudo will change to before executing the > command. For example: > > someuser ALL = CHROOT=/var/www /bin/sh > > will result in /bin/sh being run inside the chroot jail /var/www > when the specific user runs "sudo sh". > > Sudo 1.9.8 included a fix for a memory leak in the set_cmnd_path() > function which can result in the "user_cmnd" variable being > freed twice, but only when processing a sudoers rule that > contains a "CHROOT" setting. This does not affect the "chroot" > Defaults setting. Only a per-rule "CHROOT" setting will trigger > the bug. > > Impact: > > The bug can only be triggered by a user that has been granted > sudo privileges using a sudoers rule that contain a "CHROOT" > setting and the rule must match the current host. If no users > have sudoers rules containing "CHROOT" there is no impact. This > feature is not commonly used. > > Workaround: > > Remove rules from the sudoers file than contain a "CHROOT" > setting if using an affected version of sudo. > > Fix: > > The bug is fixed in sudo 1.9.13p2. Download attachment "signature.asc" of type "application/pgp-signature" (229 bytes)
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