vfs/proc/kcore, x86/mm/kcore: Fix SMAP fault when dumping vsyscall user page
authorJia Zhang <zhang.jia@linux.alibaba.com>
Mon, 12 Feb 2018 14:44:53 +0000 (22:44 +0800)
committerIngo Molnar <mingo@kernel.org>
Tue, 13 Feb 2018 08:15:58 +0000 (09:15 +0100)
commit595dd46ebfc10be041a365d0a3fa99df50b6ba73
tree3e781a635cad1504225e1753289d7ffecb1d8a6f
parentaec6487e994d2f625197970a56a4aac40c2c7547
vfs/proc/kcore, x86/mm/kcore: Fix SMAP fault when dumping vsyscall user page

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>
arch/x86/mm/init_64.c
fs/proc/kcore.c
include/linux/kcore.h