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| author | Richard Weinberger <richard@nod.at> | 2020-11-16 22:05:30 +0100 |
|---|---|---|
| committer | Richard Weinberger <richard@nod.at> | 2020-12-13 21:57:20 +0100 |
| commit | 20f1431160c6b590cdc269a846fc5a448abf5b98 (patch) | |
| tree | 5132362b34e3496054ec56c71fc1c3e4a41c9cf0 /fs/ubifs | |
| parent | 619ea229e9b54e65955f8746a31ae15797d297fc (diff) | |
| download | lwn-20f1431160c6b590cdc269a846fc5a448abf5b98.tar.gz lwn-20f1431160c6b590cdc269a846fc5a448abf5b98.zip | |
ubifs: wbuf: Don't leak kernel memory to flash
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>
Diffstat (limited to 'fs/ubifs')
| -rw-r--r-- | fs/ubifs/io.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c index 2dc933f73165..a9cabb3fa64c 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; |