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ubifs: wbuf: Don't leak kernel memory to flash
commit20f1431160
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:1e51764a3c
("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>
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1 changed files with 11 additions and 2 deletions
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@ -331,7 +331,7 @@ void ubifs_pad(const struct ubifs_info *c, void *buf, int pad)
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{
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uint32_t crc;
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ubifs_assert(pad >= 0 && !(pad & 7));
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ubifs_assert(pad >= 0);
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if (pad >= UBIFS_PAD_NODE_SZ) {
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struct ubifs_ch *ch = buf;
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@ -727,6 +727,10 @@ int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len)
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* write-buffer.
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*/
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memcpy(wbuf->buf + wbuf->used, buf, len);
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if (aligned_len > len) {
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ubifs_assert(aligned_len - len < 8);
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ubifs_pad(c, wbuf->buf + wbuf->used + len, aligned_len - len);
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}
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if (aligned_len == wbuf->avail) {
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dbg_io("flush jhead %s wbuf to LEB %d:%d",
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@ -819,13 +823,18 @@ int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len)
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}
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spin_lock(&wbuf->lock);
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if (aligned_len)
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if (aligned_len) {
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/*
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* And now we have what's left and what does not take whole
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* max. write unit, so write it to the write-buffer and we are
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* done.
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*/
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memcpy(wbuf->buf, buf + written, len);
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if (aligned_len > len) {
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ubifs_assert(aligned_len - len < 8);
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ubifs_pad(c, wbuf->buf + len, aligned_len - len);
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}
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}
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if (c->leb_size - wbuf->offs >= c->max_write_size)
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wbuf->size = c->max_write_size;
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