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[PULL 12/16] vvfat: Fix vvfat_write() for writes before the root directo
From: |
Kevin Wolf |
Subject: |
[PULL 12/16] vvfat: Fix vvfat_write() for writes before the root directory |
Date: |
Fri, 14 Jan 2022 14:52:22 +0100 |
The calculation in sector2cluster() is done relative to the offset of
the root directory. Any writes to blocks before the start of the root
directory (in particular, writes to the FAT) result in negative values,
which are not handled correctly in vvfat_write().
This changes sector2cluster() to return a signed value, and makes sure
that vvfat_write() doesn't try to find mappings for negative cluster
number. It clarifies the code in vvfat_write() to make it more obvious
that the cluster numbers can be negative.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20211209152231.23756-1-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
block/vvfat.c | 30 ++++++++++++++++++++++--------
1 file changed, 22 insertions(+), 8 deletions(-)
diff --git a/block/vvfat.c b/block/vvfat.c
index 36e73d4c64..b2b58d93b8 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -882,7 +882,7 @@ static int read_directory(BDRVVVFATState* s, int
mapping_index)
return 0;
}
-static inline uint32_t sector2cluster(BDRVVVFATState* s,off_t sector_num)
+static inline int32_t sector2cluster(BDRVVVFATState* s,off_t sector_num)
{
return (sector_num - s->offset_to_root_dir) / s->sectors_per_cluster;
}
@@ -2981,6 +2981,7 @@ static int vvfat_write(BlockDriverState *bs, int64_t
sector_num,
{
BDRVVVFATState *s = bs->opaque;
int i, ret;
+ int first_cluster, last_cluster;
DLOG(checkpoint());
@@ -2999,9 +3000,20 @@ DLOG(checkpoint());
if (sector_num < s->offset_to_fat)
return -1;
- for (i = sector2cluster(s, sector_num);
- i <= sector2cluster(s, sector_num + nb_sectors - 1);) {
- mapping_t* mapping = find_mapping_for_cluster(s, i);
+ /*
+ * Values will be negative for writes to the FAT, which is located before
+ * the root directory.
+ */
+ first_cluster = sector2cluster(s, sector_num);
+ last_cluster = sector2cluster(s, sector_num + nb_sectors - 1);
+
+ for (i = first_cluster; i <= last_cluster;) {
+ mapping_t *mapping = NULL;
+
+ if (i >= 0) {
+ mapping = find_mapping_for_cluster(s, i);
+ }
+
if (mapping) {
if (mapping->read_only) {
fprintf(stderr, "Tried to write to write-protected file %s\n",
@@ -3041,8 +3053,9 @@ DLOG(checkpoint());
}
}
i = mapping->end;
- } else
+ } else {
i++;
+ }
}
/*
@@ -3056,10 +3069,11 @@ DLOG(fprintf(stderr, "Write to qcow backend: %d +
%d\n", (int)sector_num, nb_sec
return ret;
}
- for (i = sector2cluster(s, sector_num);
- i <= sector2cluster(s, sector_num + nb_sectors - 1); i++)
- if (i >= 0)
+ for (i = first_cluster; i <= last_cluster; i++) {
+ if (i >= 0) {
s->used_clusters[i] |= USED_ALLOCATED;
+ }
+ }
DLOG(checkpoint());
/* TODO: add timeout */
--
2.31.1
- [PULL 02/16] include/sysemu/blockdev.h: remove drive_mark_claimed_by_board and inline drive_def, (continued)
- [PULL 02/16] include/sysemu/blockdev.h: remove drive_mark_claimed_by_board and inline drive_def, Kevin Wolf, 2022/01/14
- [PULL 01/16] block_int: make bdrv_backing_overridden static, Kevin Wolf, 2022/01/14
- [PULL 04/16] softmmu: fix device deletion events with -device JSON syntax, Kevin Wolf, 2022/01/14
- [PULL 03/16] include/sysemu/blockdev.h: remove drive_get_max_devs, Kevin Wolf, 2022/01/14
- [PULL 06/16] qemu-storage-daemon: Add vhost-user-blk help, Kevin Wolf, 2022/01/14
- [PULL 05/16] docs: Correct 'vhost-user-blk' spelling, Kevin Wolf, 2022/01/14
- [PULL 08/16] block-backend: prevent dangling BDS pointers across aio_poll(), Kevin Wolf, 2022/01/14
- [PULL 07/16] qapi/block: Restrict vhost-user-blk to CONFIG_VHOST_USER_BLK_SERVER, Kevin Wolf, 2022/01/14
- [PULL 10/16] iotests/308: Fix for CAP_DAC_OVERRIDE, Kevin Wolf, 2022/01/14
- [PULL 12/16] vvfat: Fix vvfat_write() for writes before the root directory,
Kevin Wolf <=
- [PULL 11/16] vvfat: Fix size of temporary qcow file, Kevin Wolf, 2022/01/14
- [PULL 16/16] iotests/testrunner.py: refactor test_field_width, Kevin Wolf, 2022/01/14
- [PULL 09/16] iotests/stream-error-on-reset: New test, Kevin Wolf, 2022/01/14
- [PULL 15/16] block: drop BLK_PERM_GRAPH_MOD, Kevin Wolf, 2022/01/14
- [PULL 13/16] iotests: Test qemu-img convert of zeroed data cluster, Kevin Wolf, 2022/01/14
- [PULL 14/16] qemu-img: make is_allocated_sectors() more efficient, Kevin Wolf, 2022/01/14
- Re: [PULL 00/16] Block layer patches, Peter Maydell, 2022/01/15