diff options
| author | Kees Cook <keescook@chromium.org> | 2014-06-06 14:37:18 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-06-06 16:08:13 -0700 |
| commit | 2ca9bb456ada8bcbdc8f77f8fc78207653bbaa92 (patch) | |
| tree | 05f8bd09ad6e9b24b735d7cf90c3167bade83050 /kernel | |
| parent | f88083005ab319abba5d0b2e4e997558245493c8 (diff) | |
sysctl: refactor sysctl string writing logic
Consolidate buffer length checking with new-line/end-of-line checking.
Additionally, instead of reading user memory twice, just do the
assignment during the loop.
This change doesn't affect the potential races here. It was already
possible to read a sysctl that was in the middle of a write. In both
cases, the string will always be NULL terminated. The pre-existing race
remains a problem to be solved.
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sysctl.c | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 3e214beabbe9..ac6847feaa83 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1717,21 +1717,18 @@ static int _proc_do_string(char *data, int maxlen, int write, } if (write) { + /* Start writing from beginning of buffer. */ len = 0; + *ppos += *lenp; p = buffer; - while (len < *lenp) { + while ((p - buffer) < *lenp && len < maxlen - 1) { if (get_user(c, p++)) return -EFAULT; if (c == 0 || c == '\n') break; - len++; + data[len++] = c; } - if (len >= maxlen) - len = maxlen-1; - if(copy_from_user(data, buffer, len)) - return -EFAULT; data[len] = 0; - *ppos += *lenp; } else { len = strlen(data); if (len > maxlen) |