From: Jia Zhang <zhang.jia@linux.alibaba.com>
Date: Mon, 12 Feb 2018 22:44:53 +0800
Subject: vfs/proc/kcore, x86/mm/kcore: Fix SMAP fault when dumping vsyscall
user page
Git-commit: 595dd46ebfc10be041a365d0a3fa99df50b6ba73
Patch-mainline: v4.16-rc2
References: bsc#1110006
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.jia@linux.alibaba.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jolsa@redhat.com
Link: http://lkml.kernel.org/r/1518446694-21124-2-git-send-email-zhang.jia@linux.alibaba.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
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
@@ -1090,8 +1090,7 @@ 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
@@ -509,6 +509,10 @@ 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,
};