[PATCH OLK-5.10 0/2] *** proc: fix ptrace access locking and error paths ***
*** BLURB HERE *** Jann Horn (2): proc: protect ptrace_may_access() with exec_update_lock (part 1) proc: Fix broken error paths for namespace links fs/proc/array.c | 6 ++++++ fs/proc/base.c | 41 ++++++++++++++++++++++++----------------- fs/proc/namespaces.c | 16 +++++++++++++++- 3 files changed, 45 insertions(+), 18 deletions(-) -- 2.22.0
From: Jann Horn <jannh@google.com> stable inclusion from stable-v5.10.261 commit ae1e630bcaac739f625822078edbaea98366930d category: bugfix bugzilla: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 6650527444dadc63d84aa939d14ecba4fadb2f69 ] Fix the easy cases where procfs currently calls ptrace_may_access() without exec_update_lock protection, where the fix is to simply add the extra lock or use mm_access(): - do_task_stat(): grab exec_update_lock - proc_pid_wchan(): grab exec_update_lock - proc_map_files_lookup(): use mm_access() instead of get_task_mm() - proc_map_files_readdir(): use mm_access() instead of get_task_mm() - proc_ns_get_link(): grab exec_update_lock - proc_ns_readlink(): grab exec_update_lock Fixes: f83ce3e6b02d ("proc: avoid information leaks to non-privileged processes") Cc: stable@vger.kernel.org Signed-off-by: Jann Horn <jannh@google.com> Link: https://patch.msgid.link/20260518-procfs-lockfix-part1-v1-1-5c3d20e0ac33@goo... Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> [ converted NULL return from mm_access() to ERR_PTR(-ESRCH) at call sites since 5.15's mm_access() returns NULL when the task has no mm ] Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Conflicts: fs/proc/array.c [Context differences.] Signed-off-by: Xia Fukun <xiafukun@huawei.com> --- fs/proc/array.c | 6 ++++++ fs/proc/base.c | 41 ++++++++++++++++++++++++----------------- fs/proc/namespaces.c | 12 ++++++++++++ 3 files changed, 42 insertions(+), 17 deletions(-) diff --git a/fs/proc/array.c b/fs/proc/array.c index 6bb4c81ba66e..98a301f02e7c 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -463,6 +463,11 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, int exit_code = task->exit_code; struct signal_struct *sig = task->signal; unsigned int seq = 1; + int ret; + + ret = down_read_killable(&task->signal->exec_update_lock); + if (ret) + return ret; state = *get_task_state(task); vsize = eip = esp = 0; @@ -644,6 +649,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, seq_puts(m, " 0"); seq_putc(m, '\n'); + up_read(&task->signal->exec_update_lock); if (mm) mmput(mm); return 0; diff --git a/fs/proc/base.c b/fs/proc/base.c index 3a3517d0c403..845897ca7e54 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -385,18 +385,24 @@ static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns, { unsigned long wchan; char symname[KSYM_NAME_LEN]; + int err; + err = down_read_killable(&task->signal->exec_update_lock); + if (err) + return err; if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) goto print0; wchan = get_wchan(task); if (wchan && !lookup_symbol_name(wchan, symname)) { seq_puts(m, symname); + up_read(&task->signal->exec_update_lock); return 0; } print0: seq_putc(m, '0'); + up_read(&task->signal->exec_update_lock); return 0; } #endif /* CONFIG_KALLSYMS */ @@ -2477,17 +2483,17 @@ static struct dentry *proc_map_files_lookup(struct inode *dir, if (!task) goto out; - result = ERR_PTR(-EACCES); - if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) - goto out_put_task; - result = ERR_PTR(-ENOENT); if (dname_to_vma_addr(dentry, &vm_start, &vm_end)) goto out_put_task; - mm = get_task_mm(task); + mm = mm_access(task, PTRACE_MODE_READ_FSCREDS); if (!mm) + mm = ERR_PTR(-ESRCH); + if (IS_ERR(mm)) { + result = ERR_CAST(mm); goto out_put_task; + } result = ERR_PTR(-EINTR); if (mmap_read_lock_killable(mm)) @@ -2536,23 +2542,24 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx) if (!task) goto out; - ret = -EACCES; - if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) - goto out_put_task; - ret = 0; if (!dir_emit_dots(file, ctx)) goto out_put_task; - mm = get_task_mm(task); + mm = mm_access(task, PTRACE_MODE_READ_FSCREDS); if (!mm) + mm = ERR_PTR(-ESRCH); + if (IS_ERR(mm)) { + ret = PTR_ERR(mm); + /* if the task has no mm, the directory should just be empty */ + if (ret == -ESRCH) + ret = 0; goto out_put_task; + } ret = mmap_read_lock_killable(mm); - if (ret) { - mmput(mm); - goto out_put_task; - } + if (ret) + goto out_put_mm; nr_files = 0; @@ -2576,8 +2583,7 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx) if (!p) { ret = -ENOMEM; mmap_read_unlock(mm); - mmput(mm); - goto out_put_task; + goto out_put_mm; } p->start = vma->vm_start; @@ -2585,7 +2591,6 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx) p->mode = vma->vm_file->f_mode; } mmap_read_unlock(mm); - mmput(mm); for (i = 0; i < nr_files; i++) { char buf[4 * sizeof(long) + 2]; /* max: %lx-%lx\0 */ @@ -2602,6 +2607,8 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx) ctx->pos++; } +out_put_mm: + mmput(mm); out_put_task: put_task_struct(task); out: diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c index 8e159fc78c0a..3a824f62dfcc 100644 --- a/fs/proc/namespaces.c +++ b/fs/proc/namespaces.c @@ -55,6 +55,10 @@ static const char *proc_ns_get_link(struct dentry *dentry, if (!task) return ERR_PTR(-EACCES); + error = down_read_killable(&task->signal->exec_update_lock); + if (error) + goto out_put_task; + if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) goto out; @@ -64,6 +68,8 @@ static const char *proc_ns_get_link(struct dentry *dentry, error = nd_jump_link(&ns_path); out: + up_read(&task->signal->exec_update_lock); +out_put_task: put_task_struct(task); return ERR_PTR(error); } @@ -80,11 +86,17 @@ static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int bufl if (!task) return res; + res = down_read_killable(&task->signal->exec_update_lock); + if (res) + goto out_put_task; + if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) { res = ns_get_name(name, sizeof(name), task, ns_ops); if (res >= 0) res = readlink_copy(buffer, buflen, name); } + up_read(&task->signal->exec_update_lock); +out_put_task: put_task_struct(task); return res; } -- 2.22.0
From: Jann Horn <jannh@google.com> mainline inclusion from mainline-v7.2-rc6 commit 425224c2d700391729be7fe6929a88ef4e2d7a4e category: bugfix bugzilla: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- Don't return the return value of down_read_killable() (0) when a ptrace access check fails, return -EACCES as intended. Reported-by: Magnus Lindholm <linmag7@gmail.com> Closes: https://lore.kernel.org/r/20260706170735.2941493-1-linmag7@gmail.com Fixes: 6650527444da ("proc: protect ptrace_may_access() with exec_update_lock (part 1)") Cc: stable@vger.kernel.org Signed-off-by: Jann Horn <jannh@google.com> Link: https://patch.msgid.link/20260706-procfs-ns-eacces-fix-v1-1-a69ab14c02e6@goo... Tested-by: Magnus Lindholm <linmag7@gmail.com> Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> Conflicts: fs/proc/namespaces.c [Context differences.] Signed-off-by: Xia Fukun <xiafukun@huawei.com> --- fs/proc/namespaces.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c index 3a824f62dfcc..3a7f1db9b7b0 100644 --- a/fs/proc/namespaces.c +++ b/fs/proc/namespaces.c @@ -46,7 +46,7 @@ static const char *proc_ns_get_link(struct dentry *dentry, const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops; struct task_struct *task; struct path ns_path; - int error = -EACCES; + int error; if (!dentry) return ERR_PTR(-ECHILD); @@ -59,6 +59,7 @@ static const char *proc_ns_get_link(struct dentry *dentry, if (error) goto out_put_task; + error = -EACCES; if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) goto out; @@ -90,6 +91,7 @@ static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int bufl if (res) goto out_put_task; + res = -EACCES; if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) { res = ns_get_name(name, sizeof(name), task, ns_ops); if (res >= 0) -- 2.22.0
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