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Commit 0337bb53 authored by Aleksa Sarai's avatar Aleksa Sarai Committed by Greg Kroah-Hartman
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procfs: block chmod on /proc/thread-self/comm 

commit ccf61486fe1e1a48e18c638d1813cda77b3c0737 upstream.

Due to an oversight in commit 1b3044e3 ("procfs: fix pthread
cross-thread naming if !PR_DUMPABLE") in switching from REG to NOD,
chmod operations on /proc/thread-self/comm were no longer blocked as
they are on almost all other procfs files.

A very similar situation with /proc/self/environ was used to as a root
exploit a long time ago, but procfs has SB_I_NOEXEC so this is simply a
correctness issue.

Ref: https://lwn.net/Articles/191954/


Ref: 6d76fa58 ("Don't allow chmod() on the /proc/<pid>/ files")
Fixes: 1b3044e3 ("procfs: fix pthread cross-thread naming if !PR_DUMPABLE")
Cc: stable@vger.kernel.org # v4.7+
Signed-off-by: default avatarAleksa Sarai <cyphar@cyphar.com>
Message-Id: <20230713141001.27046-1-cyphar@cyphar.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2e1f12ce

fs/proc/base.c

+2 −1
Original line number Diff line number Diff line
@@ -3412,6 +3412,7 @@ static int proc_tid_comm_permission(struct inode *inode, int mask) 
}



static const struct inode_operations proc_tid_comm_inode_operations = {

		.setattr	= proc_setattr,

		.permission	= proc_tid_comm_permission,

};