From ff7ec8dc1b646296f8d94c39339e8d3833d16c05 Mon Sep 17 00:00:00 2001
From: wangzijie <wangzijie1@honor.com>
Date: Sat, 7 Jun 2025 10:13:53 +0800
Subject: proc: use the same treatment to check proc_lseek as ones for
 proc_read_iter et.al

Check pde->proc_ops->proc_lseek directly may cause UAF in rmmod scenario.
It's a gap in proc_reg_open() after commit 654b33ada4ab("proc: fix UAF in
proc_get_inode()").  Followed by AI Viro's suggestion, fix it in same
manner.

Link: https://lkml.kernel.org/r/20250607021353.1127963-1-wangzijie1@honor.com
Fixes: 3f61631d47f1 ("take care to handle NULL ->proc_lseek()")
Signed-off-by: wangzijie <wangzijie1@honor.com>
Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 include/linux/proc_fs.h | 1 +
 1 file changed, 1 insertion(+)

(limited to 'include')

diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index ea62201c74c4..703d0c76cc9a 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -27,6 +27,7 @@ enum {
 
 	PROC_ENTRY_proc_read_iter	= 1U << 1,
 	PROC_ENTRY_proc_compat_ioctl	= 1U << 2,
+	PROC_ENTRY_proc_lseek		= 1U << 3,
 };
 
 struct proc_ops {
-- 
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