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authorChristoph Hellwig <hch@lst.de>2020-06-08 21:35:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-09 09:39:16 -0700
commit2a71e81d32198785387c8bc0f2cc5d78f84e2e78 (patch)
tree8fae2ecb69aa0286ab0e2c7fe9e3ca3678f37251 /mm
parentfa94111d94354de76c47fea6e1187d1ee91e23a7 (diff)
maccess: return -ERANGE when probe_kernel_read() fails
Allow the callers to distinguish a real unmapped address vs a range that can't be probed. Suggested-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20200521152301.2587579-24-hch@lst.de Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/maccess.c16
1 files changed, 9 insertions, 7 deletions
diff --git a/mm/maccess.c b/mm/maccess.c
index db7cf48d8fed..88845eda5047 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -24,7 +24,7 @@ bool __weak probe_kernel_read_allowed(const void *unsafe_src, size_t size)
long probe_kernel_read(void *dst, const void *src, size_t size)
{
if (!probe_kernel_read_allowed(src, size))
- return -EFAULT;
+ return -ERANGE;
pagefault_disable();
probe_kernel_read_loop(dst, src, size, u64, Efault);
@@ -68,7 +68,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
if (unlikely(count <= 0))
return 0;
if (!probe_kernel_read_allowed(unsafe_addr, count))
- return -EFAULT;
+ return -ERANGE;
pagefault_disable();
do {
@@ -93,7 +93,8 @@ Efault:
* @size: size of the data chunk
*
* Safely read from kernel address @src to the buffer at @dst. If a kernel
- * fault happens, handle that and return -EFAULT.
+ * fault happens, handle that and return -EFAULT. If @src is not a valid kernel
+ * address, return -ERANGE.
*
* We ensure that the copy_from_user is executed in atomic context so that
* do_page_fault() doesn't attempt to take mmap_lock. This makes
@@ -106,7 +107,7 @@ long probe_kernel_read(void *dst, const void *src, size_t size)
mm_segment_t old_fs = get_fs();
if (!probe_kernel_read_allowed(src, size))
- return -EFAULT;
+ return -ERANGE;
set_fs(KERNEL_DS);
pagefault_disable();
@@ -158,8 +159,9 @@ long probe_kernel_write(void *dst, const void *src, size_t size)
*
* On success, returns the length of the string INCLUDING the trailing NUL.
*
- * If access fails, returns -EFAULT (some data may have been copied
- * and the trailing NUL added).
+ * If access fails, returns -EFAULT (some data may have been copied and the
+ * trailing NUL added). If @unsafe_addr is not a valid kernel address, return
+ * -ERANGE.
*
* If @count is smaller than the length of the string, copies @count-1 bytes,
* sets the last byte of @dst buffer to NUL and returns @count.
@@ -173,7 +175,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
if (unlikely(count <= 0))
return 0;
if (!probe_kernel_read_allowed(unsafe_addr, count))
- return -EFAULT;
+ return -ERANGE;
set_fs(KERNEL_DS);
pagefault_disable();