The patch titled Subject: proc: fix missing pde_set_flags() for net proc files has been added to the -mm mm-hotfixes-unstable branch. Its filename is proc-fix-missing-pde_set_flags-for-net-proc-files.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: wangzijie wangzijie1@honor.com 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().

[1]: https://lore.kernel.org/all/20250815195616.64497967@chagall.paradoxon.rec/

Link: https://lkml.kernel.org/r/20250818123102.959595-1-wangzijie1@honor.com Fixes: ff7ec8dc1b64 ("proc: use the same treatment to check proc_lseek as ones for proc_read_iter et.al) Signed-off-by: wangzijie wangzijie1@honor.com Reported-by: Lars Wendler polynomial-c@gmx.de Cc: Alexei Starovoitov ast@kernel.org Cc: Alexey Dobriyan adobriyan@gmail.com 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 k.shutemov@gmail.com Cc: wangzijie wangzijie1@honor.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/proc/generic.c | 36 +++++++++++++++++++----------------- 1 file changed, 19 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 +367,23 @@ static const struct inode_operations pro .setattr = proc_notify_change, };

+static void pde_set_flags(struct proc_dir_entry *pde) +{ + if (!pde->proc_ops) + return; + + 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; +} + /* 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 +391,8 @@ 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 +580,6 @@ 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 +590,6 @@ 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 +640,6 @@ 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 +670,6 @@ 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

proc-fix-missing-pde_set_flags-for-net-proc-files.patch