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xen/xenbus: Add __counted_by for struct read_buffer and use struct_size()

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Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for
array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

While there, use struct_size() helper, instead of the open-coded
version, to calculate the size for the allocation of the whole
flexible structure, including of course, the flexible-array member.

This code was found with the help of Coccinelle, and audited and
fixed manually.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Jason Andryuk <jandryuk@gmail.com>
Link: https://lore.kernel.org/r/ZSRMosLuJJS5Y/io@work
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Gustavo A. R. Silva 2023-10-09 12:55:30 -06:00 committed by Juergen Gross
parent 44961b81a9
commit d3a2b6b48f
1 changed files with 2 additions and 2 deletions
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4
drivers/xen/xenbus/xenbus_dev_frontend.c
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@ -82,7 +82,7 @@ struct read_buffer {
struct list_head list; struct list_head list;
unsigned int cons; unsigned int cons;
unsigned int len; unsigned int len;
char msg[]; char msg[] __counted_by(len);
}; };
struct xenbus_file_priv { struct xenbus_file_priv {
@ -195,7 +195,7 @@ static int queue_reply(struct list_head *queue, const void *data, size_t len)
if (len > XENSTORE_PAYLOAD_MAX) if (len > XENSTORE_PAYLOAD_MAX)
return -EINVAL; return -EINVAL;
rb = kmalloc(sizeof(*rb) + len, GFP_KERNEL); rb = kmalloc(struct_size(rb, msg, len), GFP_KERNEL);
if (rb == NULL) if (rb == NULL)
return -ENOMEM; return -ENOMEM;