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qmp: Fix design bug and read beyond buffer in memchar-write

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Command memchar-write takes data and size parameter.  Begs the
question what happens when data doesn't match size.

With format base64, qmp_memchar_write() copies the full data argument,
regardless of size argument.

With format utf8, qmp_memchar_write() copies size bytes from data,
happily reading beyond data.  Copies crap from the heap or even
crashes.

Drop the size parameter, and always copy the full data argument.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Markus Armbruster 2013-02-06 21:27:14 +01:00 committed by Anthony Liguori
parent 15af6321f4
commit 82e59a676c
4 changed files with 6 additions and 14 deletions
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4
hmp.c
View File

@ -664,13 +664,11 @@ void hmp_pmemsave(Monitor *mon, const QDict *qdict)
void hmp_memchar_write(Monitor *mon, const QDict *qdict)
{
uint32_t size;
const char *chardev = qdict_get_str(qdict, "device");
const char *data = qdict_get_str(qdict, "data");
Error *errp = NULL;
size = strlen(data);
qmp_memchar_write(chardev, size, data, false, 0, &errp);
qmp_memchar_write(chardev, data, false, 0, &errp);
hmp_handle_error(mon, &errp);
}

4
qapi-schema.json
View File

@ -346,8 +346,6 @@
#
# @device: the name of the memory char device.
#
# @size: the size to write in bytes.
#
# @data: the source data write to memchar.
#
# @format: #optional the format of the data write to chardev 'memory',
@ -359,7 +357,7 @@
# Since: 1.4
##
{ 'command': 'memchar-write',
'data': {'device': 'str', 'size': 'int', 'data': 'str',
'data': {'device': 'str', 'data': 'str',
'*format': 'DataFormat'} }
##

8
qemu-char.c
View File

@ -2753,9 +2753,8 @@ static bool qemu_is_chr(const CharDriverState *chr, const char *filename)
return strcmp(chr->filename, filename);
}
void qmp_memchar_write(const char *device, int64_t size,
const char *data, bool has_format,
enum DataFormat format,
void qmp_memchar_write(const char *device, const char *data,
bool has_format, enum DataFormat format,
Error **errp)
{
CharDriverState *chr;
@ -2774,12 +2773,11 @@ void qmp_memchar_write(const char *device, int64_t size,
return;
}
write_count = (gsize)size;
if (has_format && (format == DATA_FORMAT_BASE64)) {
write_data = g_base64_decode(data, &write_count);
} else {
write_data = (uint8_t *)data;
write_count = strlen(data);
}
ret = cirmem_chr_write(chr, write_data, write_count);

4
qmp-commands.hx
View File

@ -467,7 +467,7 @@ EQMP
{
.name = "memchar-write",
.args_type = "device:s,size:i,data:s,format:s?",
.args_type = "device:s,data:s,format:s?",
.mhandler.cmd_new = qmp_marshal_input_memchar_write,
},
@ -481,7 +481,6 @@ char device.
Arguments:
- "device": the name of the char device, must be unique (json-string)
- "size": the memory size, in bytes, should be power of 2 (json-int)
- "data": the source data write to memory (json-string)
- "format": the data format write to memory, default is
utf8. (json-string, optional)
@ -491,7 +490,6 @@ Example:
-> { "execute": "memchar-write",
"arguments": { "device": foo,
"size": 8,
"data": "abcdefgh",
"format": "utf8" } }
<- { "return": {} }