On Tue, Jun 18, 2024 at 03:45:22PM -0700, Andrii Nakryiko wrote:
> The need to get ELF build ID reliably is an important aspect when
> dealing with profiling and stack trace symbolization, and
> /proc/<pid>/maps textual representation doesn't help with this.
> @@ -539,6 +543,21 @@ static int do_procmap_query(struct proc_maps_private *priv, void __user *uarg)
> }
> }
>
> + if (karg.build_id_size) {
> + __u32 build_id_sz;
> +
> + err = build_id_parse(vma, build_id_buf, &build_id_sz);
This is not your bug but build_id_parse() assumes program headers
immediately follow ELF header which is not guaranteed.
> + * If this field is set to non-zero value, build_id_addr should point
> + * to valid user space memory buffer of at least build_id_size bytes.
> + * If set to zero, build_id_addr should be set to zero as well
> + */
> + __u32 build_id_size; /* in/out */
> /*
> * User-supplied address of a buffer of at least vma_name_size bytes
> * for kernel to fill with matched VMA's name (see vma_name_size field
> @@ -519,6 +539,14 @@ struct procmap_query {
> * Should be set to zero if VMA name should not be returned.
> */
> __u64 vma_name_addr; /* in */
> + /*
> + * User-supplied address of a buffer of at least build_id_size bytes
> + * for kernel to fill with matched VMA's ELF build ID, if available
> + * (see build_id_size field description above for details).
> + *
> + * Should be set to zero if build ID should not be returned.
> + */
> + __u64 build_id_addr; /* in */
Can this be simplified to 512-bit buffer in ioctl structure?
BUILD_ID_SIZE_MAX is 20 which is sha1.
