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

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[ 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 <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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jia Zhang 2018-02-12 22:44:53 +08:00 committed by Greg Kroah-Hartman
parent c064b7c1d2
commit f4d6e4598a
3 changed files with 6 additions and 2 deletions
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3
arch/x86/mm/init_64.c
View File

@ -1180,8 +1180,7 @@ 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);
}

4
fs/proc/kcore.c
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@ -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)) {
/*

1
include/linux/kcore.h
View File

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