On 9/23/26 14:53, Bill Wendling wrote:
Add the "__counted_by_ptr" attribute to the buffer field of "struct
vmbus_gpadl". This allows compilers (GCC and Clang) to perform
compile-time and runtime bounds-checking when KASAN is enabled, preventing
potential out-of-bounds accesses to the GPADL buffer.
The fields "buffer" and "size" of "struct vmbus_gpadl" are assigned
exactly once, during GPADL establishment inside
"__vmbus_establish_gpadl()" in "drivers/hv/channel.c".
To ensure that the count field ("size") is initialized before the
pointer field ("buffer") is assigned, we reorder the assignments in
"__vmbus_establish_gpadl()" so that "gpadl->size" is written before
"gpadl->buffer".
Cc: [email protected]
Assisted-by: LLM
Signed-off-by: Bill Wendling <[email protected]>
---
drivers/hv/channel.c | 2 +-
include/linux/hyperv.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 7e4cc6f55237..7042de2dd481 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -548,8 +548,8 @@ static int __vmbus_establish_gpadl(struct vmbus_channel
*channel,
/* At this point, we received the gpadl created msg */
gpadl->gpadl_handle = gpadlmsg->gpadl;
- gpadl->buffer = kbuffer;
gpadl->size = size;
+ gpadl->buffer = kbuffer;
I think in some cases these subtle changes are worth a short but
informative comment saying that the _counter_ must be initialized
before the first reference to the pointer.
We can see this as part of the learning curve people have to go
through before the counted_by annotations and their requirements
are more widely known and understood. But I guess this can be
handled on a case-by-case basis.
Regardless:
Reviewed-by: Gustavo A. R. Silva <[email protected]>
Thanks
-Gustavo
cleanup:
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 9e109d91aa14..408748a05440 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -780,7 +780,7 @@ struct vmbus_device {
struct vmbus_gpadl {
u32 gpadl_handle;
u32 size;
- void *buffer;
+ void *buffer __counted_by_ptr(size);
bool decrypted;
};
