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author | Alexei Starovoitov <ast@plumgrid.com> | 2015-08-31 18:57:10 +0300 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2015-08-31 22:36:10 +0300 |
commit | dbb7ee0e474cc8221de55583f516275693c5b552 (patch) | |
tree | 1b3a02e7a92051b57922775bbbd977e69ddcbd2d /mm | |
parent | 9dc30648f0708cf063e29470d83f63f8dc8fc430 (diff) | |
download | linux-dbb7ee0e474cc8221de55583f516275693c5b552.tar.xz |
lib: move strncpy_from_unsafe() into mm/maccess.c
To fix build errors:
kernel/built-in.o: In function `bpf_trace_printk':
bpf_trace.c:(.text+0x11a254): undefined reference to `strncpy_from_unsafe'
kernel/built-in.o: In function `fetch_memory_string':
trace_kprobe.c:(.text+0x11acf8): undefined reference to `strncpy_from_unsafe'
move strncpy_from_unsafe() next to probe_kernel_read/write()
which use the same memory access style.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Fixes: 1a6877b9c0c2 ("lib: introduce strncpy_from_unsafe()")
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/maccess.c | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/mm/maccess.c b/mm/maccess.c index d53adf9ba84b..34fe24759ed1 100644 --- a/mm/maccess.c +++ b/mm/maccess.c @@ -60,3 +60,44 @@ long __probe_kernel_write(void *dst, const void *src, size_t size) return ret ? -EFAULT : 0; } EXPORT_SYMBOL_GPL(probe_kernel_write); + +/** + * strncpy_from_unsafe: - Copy a NUL terminated string from unsafe address. + * @dst: Destination address, in kernel space. This buffer must be at + * least @count bytes long. + * @src: Unsafe address. + * @count: Maximum number of bytes to copy, including the trailing NUL. + * + * Copies a NUL-terminated string from unsafe address to kernel buffer. + * + * 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 @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. + */ +long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count) +{ + mm_segment_t old_fs = get_fs(); + const void *src = unsafe_addr; + long ret; + + if (unlikely(count <= 0)) + return 0; + + set_fs(KERNEL_DS); + pagefault_disable(); + + do { + ret = __copy_from_user_inatomic(dst++, + (const void __user __force *)src++, 1); + } while (dst[-1] && ret == 0 && src - unsafe_addr < count); + + dst[-1] = '\0'; + pagefault_enable(); + set_fs(old_fs); + + return ret < 0 ? ret : src - unsafe_addr; +} |