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authorRichard Weinberger <richard@nod.at>2020-11-16 22:05:30 +0100
committerRichard Weinberger <richard@nod.at>2020-12-13 21:57:20 +0100
commit20f1431160c6b590cdc269a846fc5a448abf5b98 (patch)
tree5132362b34e3496054ec56c71fc1c3e4a41c9cf0
parentubi: Remove useless code in bytes_str_to_int (diff)
downloadlinux-20f1431160c6b590cdc269a846fc5a448abf5b98.tar.xz
linux-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>
-rw-r--r--fs/ubifs/io.c13
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;