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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>
This commit is contained in:
Jim Meyering 2012-10-04 13:09:47 +02:00 committed by Anthony Liguori
parent c2cba3d931
commit 3178e2755e
1 changed files with 22 additions and 12 deletions
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34
block/sheepdog.c
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@ -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++;
}
}