libibverbs: Skip zero-length memcpy in fill_attr_in() #1669
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fill_attr_in() unconditionally calls memcpy() when len <= sizeof(u64), even if len is zero. In commit d9af497 ("verbs: Add ibv_cmd_alloc/free commands for DMA handle"), the call fill_attr_in_enum(cmdb, UVERBS_ATTR_ALLOC_DMAH_TPH_MEM_TYPE, attr->tph_mem_type, NULL, 0); started passing a NULL data pointer together with len == 0, which leads to memcpy() being invoked with a NULL source address. While nothing is actually copied, some compilers and sanitizers treat this as undefined behavior and emit errors. Avoid this by skipping memcpy() when len is zero. Zero-length attributes have no payload, so this does not change behaviour. fill_attr_in() was originally introduced in commit c344635 ("verbs: Add basic infrastructure support for the kabi ioctl"). Fixes: d9af497 ("verbs: Add ibv_cmd_alloc/free commands for DMA handle") Signed-off-by: Yijing Zeng <zengyijing19900106@gmail.com>
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fill_attr_in() unconditionally calls memcpy() when len <= sizeof(u64), even if len is zero. In commit d9af497 ("verbs: Add ibv_cmd_alloc/free commands for DMA handle"), the call
started passing a NULL data pointer together with len == 0, which leads to memcpy() being invoked with a NULL source address. While nothing is actually copied, some compilers and sanitizers treat this as undefined behavior and emit errors.
Avoid this by skipping memcpy() when len is zero. Zero-length attributes have no payload, so this does not change behavior.
fill_attr_in() was originally introduced in commit c344635 ("verbs: Add basic infrastructure support for the kabi ioctl").
Fixes: d9af497 ("verbs: Add ibv_cmd_alloc/free commands for DMA handle")
Signed-off-by: Yijing Zeng zengyijing19900106@gmail.com