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Re: [PATCH v6 01/10] parallels: Out of image offset in BAT leads to imag


From: Denis V. Lunev
Subject: Re: [PATCH v6 01/10] parallels: Out of image offset in BAT leads to image inflation
Date: Fri, 26 Aug 2022 14:54:54 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0

On 25.08.2022 16:31, Alexander Ivanov wrote:
data_end field in BDRVParallelsState is set to the biggest offset present
in BAT. If this offset is outside of the image, any further write will create
the cluster at this offset and/or the image will be truncated to this
offset on close. This is definitely not correct.
Raise an error in parallels_open() if data_end points outside the image and
it is not a check (let the check to repaire the image).
Set data_end to the end of the cluster with the last correct offset.

Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
---
  block/parallels.c | 17 +++++++++++++++++
  1 file changed, 17 insertions(+)

diff --git a/block/parallels.c b/block/parallels.c
index a229c06f25..93bc2750ef 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -732,6 +732,7 @@ static int parallels_open(BlockDriverState *bs, QDict 
*options, int flags,
      BDRVParallelsState *s = bs->opaque;
      ParallelsHeader ph;
      int ret, size, i;
+    int64_t file_size;
      QemuOpts *opts = NULL;
      Error *local_err = NULL;
      char *buf;
@@ -742,6 +743,12 @@ static int parallels_open(BlockDriverState *bs, QDict 
*options, int flags,
          return -EINVAL;
      }
+ file_size = bdrv_getlength(bs->file->bs);
+    if (file_size < 0) {
+        return -EINVAL;
+    }
+    file_size >>= BDRV_SECTOR_BITS;
+
      ret = bdrv_pread(bs->file, 0, sizeof(ph), &ph, 0);
      if (ret < 0) {
          goto fail;
@@ -806,6 +813,16 @@ static int parallels_open(BlockDriverState *bs, QDict 
*options, int flags,
for (i = 0; i < s->bat_size; i++) {
          int64_t off = bat2sect(s, i);
+        if (off >= file_size) {
+            if (flags & BDRV_O_CHECK) {
+                continue;
+            }
+            error_setg(errp, "parallels: Offset %" PRIi64 " in BAT[%d] entry "
+                       "is larger than file size (%" PRIi64 ")",
+                       off, i, file_size);
+            ret = -EINVAL;
+            goto fail;
+        }
          if (off >= s->data_end) {
              s->data_end = off + s->tracks;
          }
with string length fixes in the commit message (more that 74 chars)

Reviewed-by: Denis V. Lunev <den@openvz.org>



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