4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jia Zhang <zhang....@linux.alibaba.com>
[ Upstream commit 595dd46ebfc10be041a365d0a3fa99df50b6ba73 ]
Commit:
df04abfd181a ("fs/proc/kcore.c: Add bounce buffer for ktext data")
... introduced a bounce buffer to work around CONFIG_HARDENED_USERCOPY=y.
However, accessing the vsyscall user page will cause an SMAP fault.
Replace memcpy() with copy_from_user() to fix this bug works, but adding
a common way to handle this sort of user page may be useful for future.
Currently, only vsyscall page requires KCORE_USER.
Signed-off-by: Jia Zhang <zhang....@linux.alibaba.com>
Reviewed-by: Jiri Olsa <jo...@kernel.org>
Cc: Al Viro <v...@zeniv.linux.org.uk>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: jo...@redhat.com
Link:
http://lkml.kernel.org/r/1518446694-21124-2-git-send-email-zhang....@linux.alibaba.com
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/x86/mm/init_64.c | 3 +--
fs/proc/kcore.c | 4 ++++
include/linux/kcore.h | 1 +
3 files changed, 6 insertions(+), 2 deletions(-)
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1014,8 +1014,7 @@ void __init mem_init(void)
after_bootmem = 1;
/* Register memory areas for /proc/kcore */
- kclist_add(&kcore_vsyscall, (void *)VSYSCALL_ADDR,
- PAGE_SIZE, KCORE_OTHER);
+ kclist_add(&kcore_vsyscall, (void *)VSYSCALL_ADDR, PAGE_SIZE,
KCORE_USER);
mem_init_print_info(NULL);
}
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -505,6 +505,10 @@ read_kcore(struct file *file, char __use
/* we have to zero-fill user buffer even if no read */
if (copy_to_user(buffer, buf, tsz))
return -EFAULT;
+ } else if (m->type == KCORE_USER) {
+ /* User page is handled prior to normal kernel page: */
+ if (copy_to_user(buffer, (char *)start, tsz))
+ return -EFAULT;
} else {
if (kern_addr_valid(start)) {
/*
--- a/include/linux/kcore.h
+++ b/include/linux/kcore.h
@@ -9,6 +9,7 @@ enum kcore_type {
KCORE_VMALLOC,
KCORE_RAM,
KCORE_VMEMMAP,
+ KCORE_USER,
KCORE_OTHER,
};
