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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id e2sm7733726pfn.141.2021.09.23.23.20.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Sep 2021 23:20:16 -0700 (PDT) From: Kees Cook To: Andrew Morton Cc: Kees Cook , kernel test robot , Vito Caputo , Jann Horn , stable@vger.kernel.org, Helge Deller , Qi Zheng , Josh Poimboeuf , "Tobin C. Harding" , Tycho Andersen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Mark Rutland , Jens Axboe , Peter Zijlstra , Andy Lutomirski , Lai Jiangshan , Stefan Metzmacher , Dave Hansen , Christian Brauner , Michal Hocko , "Eric W. Biederman" , Randy Dunlap , Ohhoon Kwon , YiFei Zhu , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, x86@kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH 1/3] Revert "proc/wchan: use printk format instead of lookup_symbol_name()" Date: Thu, 23 Sep 2021 23:20:04 -0700 Message-Id: <20210924062006.231699-2-keescook@chromium.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210924062006.231699-1-keescook@chromium.org> References: <20210924062006.231699-1-keescook@chromium.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1921; h=from:subject; bh=48rNinxgYhX0MMt+z9ytmuG8GHuOw2IZ5/XYplBnCcc=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBhTW4V3aAmkY3cNkeh8mx6qR4Wd4ABLM9VfEd7+ihZ Bx7vHSCJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCYU1uFQAKCRCJcvTf3G3AJnoXD/ 9+ie60XyWvsYauLjXuepEjG45dMmVfHo8TJw7OCNXZ2lTIe5ZGlf6Rx4OVEwn44n4dTUH8avAsCeKU tw8F1HJKdyRsL3NojF9a7XLqhrfqcnRaDkh/0BQejpIToUmgWFrtjFdKlKi0AfADEqEiMAqi7JHSZj lE1dM2Vxe1Paqq79EITBohvHgYebZ3WrG4OuDaw1Vxpy8DoeElQfU+5pcvDokYbIls5rQAnAH4AtUp TVlgob8YzJvqYTYCDyIb9yxXKG7NAaY16IKLIhgnxcu75kkVFJ9CDRNIj1YHu7bbosm4rYpS7zACEM 0X2UGQ5R4jMA2jP2jP5CeNr3hotGrlZ8rtZ/SkhcWdcgu6Br7T4YnrAo6o99k7unwja/t4wugVSbcc sm7ZrehQY2OqsB/m7q4ClgVslqFfVcJRTvXlrAQJoQuCp419WQ90WLqdWheX1fZmu+kILVE2c3Zz28 fSCWDwW2Tc/g4VxVVqtjtiZkSZxBkcfyzt0e9R/Aciv2Y+Z95MtshjPERDwO6BaarMumHYWcwmMG+Z uBdVf6svZlcVnsn3J4HEnNZlk47ez87SpbihS9Vud0VBydXWwYsXBTLtFi9yT/EzMIG1INYJ62cs1B w/bp15u2DxJQTfDAKRvzhLl7s/oYbFUbxJ+vogxQzPbKDzPi2NQ4UKbDo4wQ== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org This reverts commit 152c432b128cb043fc107e8f211195fe94b2159c. When a kernel address couldn't be symbolized for /proc/$pid/wchan, it would leak the raw value, a potential information exposure. This is a regression compared to the safer pre-v5.12 behavior. Reported-by: kernel test robot Link: https://lore.kernel.org/all/20210103142726.GC30643@xsang-OptiPlex-9020/ Reported-by: Vito Caputo Link: https://lore.kernel.org/lkml/20210921193249.el476vlhg5k6lfcq@shells.gnugeneration.com/ Reported-by: Jann Horn Link: https://lore.kernel.org/lkml/CAG48ez2zC=+PuNgezH53HBPZ8CXU5H=vkWx7nJs60G8RXt3w0Q@mail.gmail.com/ Cc: stable@vger.kernel.org Signed-off-by: Kees Cook Acked-by: Helge Deller --- fs/proc/base.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index 533d5836eb9a..1f394095eb88 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -67,6 +67,7 @@ #include #include #include +#include #include #include #include @@ -386,17 +387,19 @@ static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns, struct pid *pid, struct task_struct *task) { unsigned long wchan; + char symname[KSYM_NAME_LEN]; - if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) - wchan = get_wchan(task); - else - wchan = 0; + if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) + goto print0; - if (wchan) - seq_printf(m, "%ps", (void *) wchan); - else - seq_putc(m, '0'); + wchan = get_wchan(task); + if (wchan && !lookup_symbol_name(wchan, symname)) { + seq_puts(m, symname); + return 0; + } +print0: + seq_putc(m, '0'); return 0; } #endif /* CONFIG_KALLSYMS */