vfs/proc/kcore, x86/mm/kcore: Fix SMAP fault when dumping vsyscall user page

Commit:

  df04abfd18 ("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>
This commit is contained in:
Jia Zhang 2018-02-12 22:44:53 +08:00 committed by Ingo Molnar
parent aec6487e99
commit 595dd46ebf
3 changed files with 6 additions and 2 deletions

View file

@ -1193,8 +1193,7 @@ void __init mem_init(void)
register_page_bootmem_info();
/* 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);
}

View file

@ -510,6 +510,10 @@ 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)) {
/*

View file

@ -10,6 +10,7 @@ enum kcore_type {
KCORE_VMALLOC,
KCORE_RAM,
KCORE_VMEMMAP,
KCORE_USER,
KCORE_OTHER,
};