linux-kernel - [PATCH] prctl: fix compat handling for prctl

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Date:   Wed, 18 Apr 2018 11:19:04 +0800
From:   Li Bin <huawei.libin@...wei.com>
To:     Al Viro <viro@...IV.linux.org.uk>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        <linux-kernel@...r.kernel.org>
CC:     <huawei.libin@...wei.com>, <guohanjun@...wei.com>
Subject: [PATCH] prctl: fix compat handling for prctl

The member auxv in prctl_mm_map structure which be shared with
userspace is pointer type, but the kernel supporting COMPAT didn't
handle it. This patch fix the compat handling for prctl syscall.

Signed-off-by: Li Bin <huawei.libin@...wei.com>
---
 kernel/sys.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/kernel/sys.c b/kernel/sys.c
index ad69218..03b9731 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1968,6 +1968,25 @@ static int validate_prctl_map(struct prctl_mm_map *prctl_map)
 	return error;
 }
 
+#ifdef CONFIG_COMPAT
+struct compat_prctl_mm_map {
+	__u64   start_code;     /* code section bounds */
+	__u64   end_code;
+	__u64   start_data;     /* data section bounds */
+	__u64   end_data;
+	__u64   start_brk;      /* heap for brk() syscall */
+	__u64   brk;
+	__u64   start_stack;        /* stack starts at */
+	__u64   arg_start;      /* command line arguments bounds */
+	__u64   arg_end;
+	__u64   env_start;      /* environment variables bounds */
+	__u64   env_end;
+	compat_uptr_t   auxv;   /* auxiliary vector */
+	__u32   auxv_size;      /* vector size */
+	__u32   exe_fd;         /* /proc/$pid/exe link file */
+};
+#endif
+
 #ifdef CONFIG_CHECKPOINT_RESTORE
 static int prctl_set_mm_map(int opt, const void __user *addr, unsigned long data_size)
 {
@@ -1986,6 +2005,28 @@ static int prctl_set_mm_map(int opt, const void __user *addr, unsigned long data
 	if (data_size != sizeof(prctl_map))
 		return -EINVAL;
 
+#ifdef CONFIG_COMPAT
+	if (is_compat_task()) {
+		struct compat_prctl_mm_map prctl_map32;
+		if (copy_from_user(&prctl_map32, addr, sizeof(prctl_map32)))
+			return -EFAULT;
+
+		prctl_map.start_code = prctl_map32.start_code;
+		prctl_map.end_code = prctl_map32.end_code;
+		prctl_map.start_data = prctl_map32.start_data;
+		prctl_map.end_data = prctl_map32.end_data;
+		prctl_map.start_brk = prctl_map32.start_brk;
+		prctl_map.brk = prctl_map32.brk;
+		prctl_map.start_stack = prctl_map32.start_stack;
+		prctl_map.arg_start = prctl_map32.arg_start;
+		prctl_map.arg_end = prctl_map32.arg_end;
+		prctl_map.env_start = prctl_map32.env_start;
+		prctl_map.env_end = prctl_map32.env_end;
+		prctl_map.auxv = compat_ptr(prctl_map32.auxv);
+		prctl_map.auxv_size = prctl_map32.auxv_size;
+		prctl_map.exe_fd = prctl_map32.exe_fd;
+	} else
+#endif
 	if (copy_from_user(&prctl_map, addr, sizeof(prctl_map)))
 		return -EFAULT;
 
-- 
1.7.12.4