[PATCH AUTOSEL for 4.9 289/293] vfs/proc/kcore, x86/mm/kcore: Fix SMAP fault when dumping vsyscall user page

[Sasha Levin]

From: Jia Zhang 

[ 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 
Reviewed-by: Jiri Olsa 
Cc: Al Viro 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
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 
Signed-off-by: Sasha Levin 
---
 arch/x86/mm/init_64.c | 3 +--
 fs/proc/kcore.c   | 4 
 include/linux/kcore.h | 1 +
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 7df8e3a79dc0..d35d0e4bbf99 100644
--- 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(_vsyscall, (void *)VSYSCALL_ADDR,
-PAGE_SIZE, KCORE_OTHER);
+   kclist_add(_vsyscall, (void *)VSYSCALL_ADDR, PAGE_SIZE, 
KCORE_USER);
 
mem_init_print_info(NULL);
 }
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index df7e07986ead..7ed961c0124f 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -505,6 +505,10 @@ read_kcore(struct file *file, char __user *buffer, size_t 
buflen, loff_t *fpos)
/* 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)) {
/*
diff --git a/include/linux/kcore.h b/include/linux/kcore.h
index d92762286645..3ffade4f2798 100644
--- 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,
 };
 
-- 
2.15.1

[PATCH AUTOSEL for 4.9 289/293] vfs/proc/kcore, x86/mm/kcore: Fix SMAP fault when dumping vsyscall user page

[Sasha Levin]

From: Jia Zhang 

[ 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 
Reviewed-by: Jiri Olsa 
Cc: Al Viro 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
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 
Signed-off-by: Sasha Levin 
---
 arch/x86/mm/init_64.c | 3 +--
 fs/proc/kcore.c   | 4 
 include/linux/kcore.h | 1 +
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 7df8e3a79dc0..d35d0e4bbf99 100644
--- 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(_vsyscall, (void *)VSYSCALL_ADDR,
-PAGE_SIZE, KCORE_OTHER);
+   kclist_add(_vsyscall, (void *)VSYSCALL_ADDR, PAGE_SIZE, 
KCORE_USER);
 
mem_init_print_info(NULL);
 }
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index df7e07986ead..7ed961c0124f 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -505,6 +505,10 @@ read_kcore(struct file *file, char __user *buffer, size_t 
buflen, loff_t *fpos)
/* 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)) {
/*
diff --git a/include/linux/kcore.h b/include/linux/kcore.h
index d92762286645..3ffade4f2798 100644
--- 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,
 };
 
-- 
2.15.1