diff options
| author | Alexander Bulekov <alxndr@bu.edu> | 2023-04-27 17:10:06 -0400 |
|---|---|---|
| committer | Michael Tokarev <mjt@tls.msk.ru> | 2023-09-11 10:53:50 +0300 |
| commit | c40ca2301c7603524eaddb5308a3f524c6f89d24 (patch) | |
| tree | 24ea2150b77a79be544e9b52a0af59203890483f /softmmu | |
| parent | 590e71e53679308f822f83ea806f580c29008964 (diff) | |
memory: prevent dma-reentracy issues
Add a flag to the DeviceState, when a device is engaged in PIO/MMIO/DMA.
This flag is set/checked prior to calling a device's MemoryRegion
handlers, and set when device code initiates DMA. The purpose of this
flag is to prevent two types of DMA-based reentrancy issues:
1.) mmio -> dma -> mmio case
2.) bh -> dma write -> mmio case
These issues have led to problems such as stack-exhaustion and
use-after-frees.
Summary of the problem from Peter Maydell:
https://lore.kernel.org/qemu-devel/CAFEAcA_23vc7hE3iaM-JVA6W38LK4hJoWae5KcknhPRD5fPBZA@mail.gmail.com
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/62
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/540
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/541
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/556
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/557
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/827
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1282
Resolves: CVE-2023-0330
Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20230427211013.2994127-2-alxndr@bu.edu>
[thuth: Replace warn_report() with warn_report_once()]
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit a2e1753b8054344f32cf94f31c6399a58794a380)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Diffstat (limited to 'softmmu')
| -rw-r--r-- | softmmu/memory.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/softmmu/memory.c b/softmmu/memory.c index bc0be3f62c..61569f8306 100644 --- a/softmmu/memory.c +++ b/softmmu/memory.c @@ -542,6 +542,18 @@ static MemTxResult access_with_adjusted_size(hwaddr addr, access_size_max = 4; } + /* Do not allow more than one simultaneous access to a device's IO Regions */ + if (mr->dev && !mr->disable_reentrancy_guard && + !mr->ram_device && !mr->ram && !mr->rom_device && !mr->readonly) { + if (mr->dev->mem_reentrancy_guard.engaged_in_io) { + warn_report_once("Blocked re-entrant IO on MemoryRegion: " + "%s at addr: 0x%" HWADDR_PRIX, + memory_region_name(mr), addr); + return MEMTX_ACCESS_ERROR; + } + mr->dev->mem_reentrancy_guard.engaged_in_io = true; + } + /* FIXME: support unaligned access? */ access_size = MAX(MIN(size, access_size_max), access_size_min); access_mask = MAKE_64BIT_MASK(0, access_size * 8); @@ -556,6 +568,9 @@ static MemTxResult access_with_adjusted_size(hwaddr addr, access_mask, attrs); } } + if (mr->dev) { + mr->dev->mem_reentrancy_guard.engaged_in_io = false; + } return r; } @@ -1170,6 +1185,7 @@ static void memory_region_do_init(MemoryRegion *mr, } mr->name = g_strdup(name); mr->owner = owner; + mr->dev = (DeviceState *) object_dynamic_cast(mr->owner, TYPE_DEVICE); mr->ram_block = NULL; if (name) { |