6.11-stable review patch. If anyone has any objections, please let me know.
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From: Tyrone Wu wudevelops@gmail.com
[ Upstream commit ad6b5b6ea9b764018249285a4fe0a2226bef4caa ]
Previously when retrieving `bpf_link_info.uprobe_multi` with `path` and `path_size` fields unset, the `path_size` field is not populated (remains 0). This behavior was inconsistent with how other input/output string buffer fields work, as the field should be populated in cases when: - both buffer and length are set (currently works as expected) - both buffer and length are unset (not working as expected)
This patch now fills the `path_size` field when `path` and `path_size` are unset.
Fixes: e56fdbfb06e2 ("bpf: Add link_info support for uprobe multi link") Signed-off-by: Tyrone Wu wudevelops@gmail.com Signed-off-by: Andrii Nakryiko andrii@kernel.org Link: https://lore.kernel.org/bpf/20241011000803.681190-1-wudevelops@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/trace/bpf_trace.c | 36 +++++++++++++++++------------------- 1 file changed, 17 insertions(+), 19 deletions(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index add26dc27d7e3..d9bc5ef1cafc3 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -3222,7 +3222,8 @@ static int bpf_uprobe_multi_link_fill_link_info(const struct bpf_link *link, struct bpf_uprobe_multi_link *umulti_link; u32 ucount = info->uprobe_multi.count; int err = 0, i; - long left; + char *p, *buf; + long left = 0;
if (!upath ^ !upath_size) return -EINVAL; @@ -3236,26 +3237,23 @@ static int bpf_uprobe_multi_link_fill_link_info(const struct bpf_link *link, info->uprobe_multi.pid = umulti_link->task ? task_pid_nr_ns(umulti_link->task, task_active_pid_ns(current)) : 0;
- if (upath) { - char *p, *buf; - - upath_size = min_t(u32, upath_size, PATH_MAX); - - buf = kmalloc(upath_size, GFP_KERNEL); - if (!buf) - return -ENOMEM; - p = d_path(&umulti_link->path, buf, upath_size); - if (IS_ERR(p)) { - kfree(buf); - return PTR_ERR(p); - } - upath_size = buf + upath_size - p; - left = copy_to_user(upath, p, upath_size); + upath_size = upath_size ? min_t(u32, upath_size, PATH_MAX) : PATH_MAX; + buf = kmalloc(upath_size, GFP_KERNEL); + if (!buf) + return -ENOMEM; + p = d_path(&umulti_link->path, buf, upath_size); + if (IS_ERR(p)) { kfree(buf); - if (left) - return -EFAULT; - info->uprobe_multi.path_size = upath_size; + return PTR_ERR(p); } + upath_size = buf + upath_size - p; + + if (upath) + left = copy_to_user(upath, p, upath_size); + kfree(buf); + if (left) + return -EFAULT; + info->uprobe_multi.path_size = upath_size;
if (!uoffsets && !ucookies && !uref_ctr_offsets) return 0;