[PATCH] prctl: fix compat handling for prctl

From: Li Bin
Date: Tue Apr 17 2018 - 23:29:26 EST


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@xxxxxxxxxx>
---
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