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authorJim Meyering <meyering@redhat.com>2012-10-04 13:09:47 +0200
committerAnthony Liguori <aliguori@us.ibm.com>2012-10-05 07:58:36 -0500
commit3178e2755ec5a7fb1afe583fb6ac2622c2c42184 (patch)
treedbb356bdbf7451a5cdec0b5d67c26267b529eef1 /block
parentc2cba3d9314f972dfaf724d0ec2d018eb54c95f1 (diff)
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sheepdog: avoid a few buffer overruns
* parse_vdiname: Use pstrcpy, not strncpy, when the destination buffer must be NUL-terminated. * sd_open: Likewise, avoid buffer overrun. * do_sd_create: Likewise. Leave the preceding memset, since pstrcpy does not NUL-fill, and filename needs that. * sd_snapshot_create: Add a comment/question. * find_vdi_name: Remove a useless memset. * sd_snapshot_goto: Remove a useless memset. Use pstrcpy to NUL-terminate, because find_vdi_name requires that its vdi arg (filename parameter) be NUL-terminated. It seems ok not to NUL-fill the buffer. Do the same for snapid: remove useless memset-0 (instead, zero tag[0]). Use pstrcpy, not strncpy. * sd_snapshot_list: Use pstrcpy, not strncpy to write into the ->name member. Each must be NUL-terminated. Acked-by: Kevin Wolf <kwolf@redhat.com> Acked-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp> Signed-off-by: Jim Meyering <meyering@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'block')
-rw-r--r--block/sheepdog.c34
1 files changed, 22 insertions, 12 deletions
diff --git a/block/sheepdog.c b/block/sheepdog.c
index 4742f8a..f35ff5b 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -866,14 +866,14 @@ static int parse_vdiname(BDRVSheepdogState *s, const char *filename,
s->port = 0;
}
- strncpy(vdi, p, SD_MAX_VDI_LEN);
+ pstrcpy(vdi, SD_MAX_VDI_LEN, p);
p = strchr(vdi, ':');
if (p) {
*p++ = '\0';
*snapid = strtoul(p, NULL, 10);
if (*snapid == 0) {
- strncpy(tag, p, SD_MAX_VDI_TAG_LEN);
+ pstrcpy(tag, SD_MAX_VDI_TAG_LEN, p);
}
} else {
*snapid = CURRENT_VDI_ID; /* search current vdi */
@@ -900,7 +900,10 @@ static int find_vdi_name(BDRVSheepdogState *s, char *filename, uint32_t snapid,
return fd;
}
- memset(buf, 0, sizeof(buf));
+ /* This pair of strncpy calls ensures that the buffer is zero-filled,
+ * which is desirable since we'll soon be sending those bytes, and
+ * don't want the send_req to read uninitialized data.
+ */
strncpy(buf, filename, SD_MAX_VDI_LEN);
strncpy(buf + SD_MAX_VDI_LEN, tag, SD_MAX_VDI_TAG_LEN);
@@ -1149,7 +1152,7 @@ static int sd_open(BlockDriverState *bs, const char *filename, int flags)
s->max_dirty_data_idx = 0;
bs->total_sectors = s->inode.vdi_size / SECTOR_SIZE;
- strncpy(s->name, vdi, sizeof(s->name));
+ pstrcpy(s->name, sizeof(s->name), vdi);
qemu_co_mutex_init(&s->lock);
g_free(buf);
return 0;
@@ -1177,8 +1180,11 @@ static int do_sd_create(char *filename, int64_t vdi_size,
return fd;
}
+ /* FIXME: would it be better to fail (e.g., return -EIO) when filename
+ * does not fit in buf? For now, just truncate and avoid buffer overrun.
+ */
memset(buf, 0, sizeof(buf));
- strncpy(buf, filename, SD_MAX_VDI_LEN);
+ pstrcpy(buf, sizeof(buf), filename);
memset(&hdr, 0, sizeof(hdr));
hdr.opcode = SD_OP_NEW_VDI;
@@ -1752,6 +1758,9 @@ static int sd_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
s->inode.vm_state_size = sn_info->vm_state_size;
s->inode.vm_clock_nsec = sn_info->vm_clock_nsec;
+ /* It appears that inode.tag does not require a NUL terminator,
+ * which means this use of strncpy is ok.
+ */
strncpy(s->inode.tag, sn_info->name, sizeof(s->inode.tag));
/* we don't need to update entire object */
datalen = SD_INODE_SIZE - sizeof(s->inode.data_vdi_id);
@@ -1811,13 +1820,13 @@ static int sd_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
memcpy(old_s, s, sizeof(BDRVSheepdogState));
- memset(vdi, 0, sizeof(vdi));
- strncpy(vdi, s->name, sizeof(vdi));
+ pstrcpy(vdi, sizeof(vdi), s->name);
- memset(tag, 0, sizeof(tag));
snapid = strtoul(snapshot_id, NULL, 10);
- if (!snapid) {
- strncpy(tag, s->name, sizeof(tag));
+ if (snapid) {
+ tag[0] = 0;
+ } else {
+ pstrcpy(tag, sizeof(tag), s->name);
}
ret = find_vdi_name(s, vdi, snapid, tag, &vid, 1);
@@ -1946,8 +1955,9 @@ static int sd_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
snprintf(sn_tab[found].id_str, sizeof(sn_tab[found].id_str), "%u",
inode.snap_id);
- strncpy(sn_tab[found].name, inode.tag,
- MIN(sizeof(sn_tab[found].name), sizeof(inode.tag)));
+ pstrcpy(sn_tab[found].name,
+ MIN(sizeof(sn_tab[found].name), sizeof(inode.tag)),
+ inode.tag);
found++;
}
}