| From foo@baz Fri Jan 15 10:49:41 AM CET 2021 |
| From: Richard Weinberger <richard@nod.at> |
| Date: Mon, 16 Nov 2020 22:05:30 +0100 |
| Subject: ubifs: wbuf: Don't leak kernel memory to flash |
| |
| From: Richard Weinberger <richard@nod.at> |
| |
| commit 20f1431160c6b590cdc269a846fc5a448abf5b98 upstream |
| |
| 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> |
| Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com> |
| Signed-off-by: Richard Weinberger <richard@nod.at> |
| [sudip: adjust context] |
| Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| fs/ubifs/io.c | 13 +++++++++++-- |
| 1 file changed, 11 insertions(+), 2 deletions(-) |
| |
| --- a/fs/ubifs/io.c |
| +++ b/fs/ubifs/io.c |
| @@ -331,7 +331,7 @@ void ubifs_pad(const struct ubifs_info * |
| { |
| uint32_t crc; |
| |
| - ubifs_assert(pad >= 0 && !(pad & 7)); |
| + ubifs_assert(pad >= 0); |
| |
| if (pad >= UBIFS_PAD_NODE_SZ) { |
| struct ubifs_ch *ch = buf; |
| @@ -721,6 +721,10 @@ int ubifs_wbuf_write_nolock(struct ubifs |
| * write-buffer. |
| */ |
| memcpy(wbuf->buf + wbuf->used, buf, len); |
| + if (aligned_len > len) { |
| + ubifs_assert(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", |
| @@ -813,13 +817,18 @@ int ubifs_wbuf_write_nolock(struct ubifs |
| } |
| |
| 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(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; |