Some code in the block layer makes potentially huge allocations. Failure
is not completely unexpected there, so avoid aborting qemu and handle
out-of-memory situations gracefully.
This patch addresses the allocations in the bochs block driver.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
Currently, seek_to_sector() returns -1 both for errors and unallocated
sectors, resulting in silent errors. As 0 is an invalid offset of data
clusters (bitmap_offset is greater than 0 because s->data_offset is
greater than 0), just return 0 for unallocated sectors and -errno in
case of error. This should then be propagated by bochs_read(), the sole
user of seek_to_sector().
That function also has a case of "return -1 in case of error", which is
fixed by this patch as well.
bochs_read() is called by bochs_co_read() which passes the return value
through, therefore it is indeed correct for bochs_read() to return
-errno.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The old check was off by a factor of 512 and didn't consider cases where
we don't get an exact division. This could lead to an out-of-bounds
array access in seek_to_sector().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
32 bit truncation could let us access the wrong offset in the image.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This fixes two possible division by zero crashes: In bochs_open() and in
seek_to_sector().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
It should neither become negative nor allow unbounded memory
allocations. This fixes aborts in g_malloc() and an s->catalog_bitmap
buffer overflow on big endian hosts.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Gets us rid of integer overflows resulting in negative sizes which
aren't correctly checked.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This is an on-disk structure, so offsets must be accurate.
Before this patch, sizeof(bochs) != sizeof(header_v1), which makes the
memcpy() between both invalid. We're lucky enough that the destination
buffer happened to be the larger one, and the memcpy size to be taken
from the smaller one, so we didn't get a buffer overflow in practice.
This patch unifies the both structures, eliminating the need to do a
memcpy in the first place. The common fields are extracted to the top
level of the struct and the actually differing part gets a union of the
two versions.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Returning "Wrong medium type" for an image that does not have a valid
header is a bit weird. Improve the error by mentioning what format
was trying to open it.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Add an Error ** parameter to BlockDriver.bdrv_open and
BlockDriver.bdrv_file_open to allow more specific error messages.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Return -errno instead of -1 on errors. While touching the
code, fix a memory leak.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This improves error reports for bochs, cow, qcow, qcow2, qed and vmdk
when a file with the wrong format is selected.
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This does the first part of the conversion to coroutines, by
wrapping bdrv_read implementations to take the mutex.
Drivers that implement bdrv_read rather than bdrv_co_readv can
then benefit from asynchronous operation (at least if the underlying
protocol supports it, which is not the case for raw-win32), even
though they still operate with a bounce buffer.
raw-win32 does not need the lock, because it cannot yield.
nbd also doesn't probably, but better be safe.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The big conversion of bdrv_read/write to coroutines caused the two
homonymous callbacks in BlockDriver to become reentrant. It goes
like this:
1) bdrv_read is now called in a coroutine, and calls bdrv_read or
bdrv_pread.
2) the nested bdrv_read goes through the fast path in bdrv_rw_co_entry;
3) in the common case when the protocol is file, bdrv_co_do_readv calls
bdrv_co_readv_em (and from here goes to bdrv_co_io_em), which yields
until the AIO operation is complete;
4) if bdrv_read had been called from a bottom half, the main loop
is free to iterate again: a device model or another bottom half
can then come and call bdrv_read again.
This applies to all four of read/write/flush/discard. It would also
apply to is_allocated, but it is not used from within coroutines:
besides qemu-img.c and qemu-io.c, which operate synchronously, the
only user is the monitor. Copy-on-read will introduce a use in the
block layer, and will require converting it.
The solution is "simply" to convert all drivers to coroutines! We
just need to add a CoMutex that is taken around affected operations.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Use bdrv_pwrite to access the backing device instead of pread, and
convert the driver to implementing the bdrv_open method which gives
it an already opened BlockDriverState for the underlying device.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Use pread instead of lseek + read in preparation of using the qemu
block API.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Format drivers shouldn't need to bother with things like file names, but rather
just get an open BlockDriverState for the underlying protocol. This patch
introduces this behaviour for bdrv_open implementation. For protocols which
need to access the filename to open their file/device/connection/... a new
callback bdrv_file_open is introduced which doesn't get an underlying file
opened.
For now, also some of the more obscure formats use bdrv_file_open because they
open() the file themselves instead of using the block.c functions. They need to
be fixed in later patches.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
CC block/bochs.o
cc1: warnings being treated as errors
block/bochs.c: In function 'seek_to_sector':
block/bochs.c:202: error: ignoring return value of 'read', declared with attribute warn_unused_result
make: *** [block/bochs.o] Error 1
Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
