Write buffers use a kmalloc()'ed buffer, they can leak up to seven bytes of kernel memory to flash if writes are not aligned. So use ubifs_pad() to fill these gaps with padding bytes. This was never a problem while scanning because the scanner logic manually aligns node lengths and skips over these gaps.
Cc: stable@vger.kernel.org Fixes: 1e51764a3c2ac05a2 ("UBIFS: add new flash file system") Signed-off-by: Richard Weinberger richard@nod.at --- fs/ubifs/io.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c index 7e4bfaf2871f..eae9cf5a57b0 100644 --- a/fs/ubifs/io.c +++ b/fs/ubifs/io.c @@ -319,7 +319,7 @@ void ubifs_pad(const struct ubifs_info *c, void *buf, int pad) { uint32_t crc;
- ubifs_assert(c, pad >= 0 && !(pad & 7)); + ubifs_assert(c, pad >= 0);
if (pad >= UBIFS_PAD_NODE_SZ) { struct ubifs_ch *ch = buf; @@ -764,6 +764,10 @@ int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len) * write-buffer. */ memcpy(wbuf->buf + wbuf->used, buf, len); + if (aligned_len > len) { + ubifs_assert(c, aligned_len - len < 8); + ubifs_pad(c, wbuf->buf + wbuf->used + len, aligned_len - len); + }
if (aligned_len == wbuf->avail) { dbg_io("flush jhead %s wbuf to LEB %d:%d", @@ -856,13 +860,18 @@ int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len) }
spin_lock(&wbuf->lock); - if (aligned_len) + if (aligned_len) { /* * And now we have what's left and what does not take whole * max. write unit, so write it to the write-buffer and we are * done. */ memcpy(wbuf->buf, buf + written, len); + if (aligned_len > len) { + ubifs_assert(c, aligned_len - len < 8); + ubifs_pad(c, wbuf->buf + len, aligned_len - len); + } + }
if (c->leb_size - wbuf->offs >= c->max_write_size) wbuf->size = c->max_write_size;