[merged mm-hotfixes-stable] proc-fix-missing-pde_set_flags-for-net-proc-files.patch removed from -mm tree
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2025-08-28 05:46:27
Also in:
mm-commits
The quilt patch titled
Subject: proc: fix missing pde_set_flags() for net proc files
has been removed from the -mm tree. Its filename was
proc-fix-missing-pde_set_flags-for-net-proc-files.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: wangzijie <redacted>
Subject: proc: fix missing pde_set_flags() for net proc files
Date: Mon, 18 Aug 2025 20:31:02 +0800
To avoid potential UAF issues during module removal races, we use
pde_set_flags() to save proc_ops flags in PDE itself before
proc_register(), and then use pde_has_proc_*() helpers instead of directly
dereferencing pde->proc_ops->*.
However, the pde_set_flags() call was missing when creating net related
proc files. This omission caused incorrect behavior which FMODE_LSEEK was
being cleared inappropriately in proc_reg_open() for net proc files. Lars
reported it in this link[1].
Fix this by ensuring pde_set_flags() is called when register proc entry,
and add NULL check for proc_ops in pde_set_flags().
[wangzijie1@honor.com: stash pde->proc_ops in a local const variable, per Christian]
Link: https://lkml.kernel.org/r/20250821105806.1453833-1-wangzijie1@honor.com
Link: https://lkml.kernel.org/r/20250818123102.959595-1-wangzijie1@honor.com
Link: https://lore.kernel.org/all/20250815195616.64497967@chagall.paradoxon.rec/ (local) [1]
Fixes: ff7ec8dc1b64 ("proc: use the same treatment to check proc_lseek as ones for proc_read_iter et.al")
Signed-off-by: wangzijie <redacted>
Reported-by: Lars Wendler <redacted>
Tested-by: Stefano Brivio <redacted>
Tested-by: Petr Van��k <redacted>
Tested by: Lars Wendler [off-list ref]
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Alexey Dobriyan <redacted>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Kirill A. Shutemov <redacted>
Cc: wangzijie <redacted>
Cc: <redacted>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
fs/proc/generic.c | 38 +++++++++++++++++++++-----------------
1 file changed, 21 insertions(+), 17 deletions(-)
--- a/fs/proc/generic.c~proc-fix-missing-pde_set_flags-for-net-proc-files
+++ a/fs/proc/generic.c@@ -367,6 +367,25 @@ static const struct inode_operations pro .setattr = proc_notify_change, }; +static void pde_set_flags(struct proc_dir_entry *pde) +{ + const struct proc_ops *proc_ops = pde->proc_ops; + + if (!proc_ops) + return; + + if (proc_ops->proc_flags & PROC_ENTRY_PERMANENT) + pde->flags |= PROC_ENTRY_PERMANENT; + if (proc_ops->proc_read_iter) + pde->flags |= PROC_ENTRY_proc_read_iter; +#ifdef CONFIG_COMPAT + if (proc_ops->proc_compat_ioctl) + pde->flags |= PROC_ENTRY_proc_compat_ioctl; +#endif + if (proc_ops->proc_lseek) + pde->flags |= PROC_ENTRY_proc_lseek; +} + /* returns the registered entry, or frees dp and returns NULL on failure */ struct proc_dir_entry *proc_register(struct proc_dir_entry *dir, struct proc_dir_entry *dp)
@@ -374,6 +393,8 @@ struct proc_dir_entry *proc_register(str if (proc_alloc_inum(&dp->low_ino)) goto out_free_entry; + pde_set_flags(dp); + write_lock(&proc_subdir_lock); dp->parent = dir; if (pde_subdir_insert(dir, dp) == false) {
@@ -561,20 +582,6 @@ struct proc_dir_entry *proc_create_reg(c return p; } -static void pde_set_flags(struct proc_dir_entry *pde) -{ - if (pde->proc_ops->proc_flags & PROC_ENTRY_PERMANENT) - pde->flags |= PROC_ENTRY_PERMANENT; - if (pde->proc_ops->proc_read_iter) - pde->flags |= PROC_ENTRY_proc_read_iter; -#ifdef CONFIG_COMPAT - if (pde->proc_ops->proc_compat_ioctl) - pde->flags |= PROC_ENTRY_proc_compat_ioctl; -#endif - if (pde->proc_ops->proc_lseek) - pde->flags |= PROC_ENTRY_proc_lseek; -} - struct proc_dir_entry *proc_create_data(const char *name, umode_t mode, struct proc_dir_entry *parent, const struct proc_ops *proc_ops, void *data)
@@ -585,7 +592,6 @@ struct proc_dir_entry *proc_create_data( if (!p) return NULL; p->proc_ops = proc_ops; - pde_set_flags(p); return proc_register(parent, p); } EXPORT_SYMBOL(proc_create_data);
@@ -636,7 +642,6 @@ struct proc_dir_entry *proc_create_seq_p p->proc_ops = &proc_seq_ops; p->seq_ops = ops; p->state_size = state_size; - pde_set_flags(p); return proc_register(parent, p); } EXPORT_SYMBOL(proc_create_seq_private);
@@ -667,7 +672,6 @@ struct proc_dir_entry *proc_create_singl return NULL; p->proc_ops = &proc_single_ops; p->single_show = show; - pde_set_flags(p); return proc_register(parent, p); } EXPORT_SYMBOL(proc_create_single_data);
_ Patches currently in -mm which might be from wangzijie1@honor.com are