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Commit 595dd46e authored by Jia Zhang's avatar Jia Zhang Committed by Ingo Molnar
Browse files

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



Commit:

  df04abfd ("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: default avatarJia Zhang <zhang.jia@linux.alibaba.com>
Reviewed-by: default avatarJiri 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: default avatarIngo Molnar <mingo@kernel.org>
parent aec6487e

arch/x86/mm/init_64.c

+1 −2
Original line number Diff line number Diff line
@@ -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);

}

fs/proc/kcore.c

+4 −0
Original line number Diff line number Diff line
@@ -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)) {

				/*

include/linux/kcore.h

+1 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ enum kcore_type { 
	KCORE_VMALLOC,

	KCORE_RAM,

	KCORE_VMEMMAP,

	KCORE_USER,

	KCORE_OTHER,

};