procfs: block chmod on /proc/thread-self/comm
commit ccf61486 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:Aleksa Sarai <cyphar@cyphar.com> Message-Id: <20230713141001.27046-1-cyphar@cyphar.com> Signed-off-by:
Christian Brauner <brauner@kernel.org> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
parent
2e1f12ce
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