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: <[email protected]>
Fixes: 1e51764a3c2ac05a2 ("UBIFS: add new flash file system")
Signed-off-by: Richard Weinberger <[email protected]>
---
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;
--
2.26.2
?? 2020/11/17 5:05, Richard Weinberger д??:
> 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: <[email protected]>
> Fixes: 1e51764a3c2ac05a2 ("UBIFS: add new flash file system")
> Signed-off-by: Richard Weinberger <[email protected]>
> ---
> 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;
>
Reviewed-by: Zhihao Cheng <[email protected]>
On Tue, Nov 17, 2020 at 2:28 AM Zhihao Cheng <[email protected]> wrote:
>
> Reviewed-by: Zhihao Cheng <[email protected]>
Thanks for reviewing, highly appreciated!
--
Thanks,
//richard
在 2020/11/17 16:43, Richard Weinberger 写道:
> On Tue, Nov 17, 2020 at 2:28 AM Zhihao Cheng <[email protected]> wrote:
>>
>> Reviewed-by: Zhihao Cheng <[email protected]>
>
> Thanks for reviewing, highly appreciated!
>
You're welcome. Actually I've been following the linux-mtd. It's just
that this patch isn't complicated, so I checked it. :-)