diff options
| author | Fuad Tabba <fuad.tabba@linux.dev> | 2026-07-13 08:28:23 +0100 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2026-07-22 16:53:29 -0400 |
| commit | 94b83ff0c0a69e42f403b59918529fbca2a89daf (patch) | |
| tree | 0e44966fea82ae4f4459c57c933b94d54a6589ad /kernel | |
| parent | 1590cf0329716306e948a8fc29f1d3ee87d3989f (diff) | |
tracing/remotes: Fix page_va[] access before counter update in trace_remote_alloc_buffer()
page_va[] is annotated __counted_by(nr_page_va), so nr_page_va must
cover an index before that element is accessed. The allocation loop
writes page_va[id] while nr_page_va is still id and increments it only
afterwards, so every write is one element past the declared count.
The store is out of bounds with respect to the annotation: a build with
CONFIG_UBSAN_BOUNDS on a toolchain that honours __counted_by
(clang >= 20.1, gcc >= 15.1) flags it as an array-index overflow.
Increment nr_page_va before writing the element it now covers. A failed
allocation then leaves the slot counted but NULL; the error path frees
it with free_page(0), which is a no-op.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260713072823.2668323-1-fuad.tabba@linux.dev
Fixes: 96e43537af546 ("tracing: Introduce trace remotes")
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
Reviewed-by: Vincent Donnefort <vdonnefort@google.com>
Tested-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace_remote.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c index 0f6ef5c36d84..ef42d9c38b37 100644 --- a/kernel/trace/trace_remote.c +++ b/kernel/trace/trace_remote.c @@ -1004,11 +1004,10 @@ int trace_remote_alloc_buffer(struct trace_buffer_desc *desc, size_t desc_size, desc->nr_cpus++; for (id = 0; id < nr_pages; id++) { + rb_desc->nr_page_va++; rb_desc->page_va[id] = (unsigned long)__get_free_page(GFP_KERNEL); if (!rb_desc->page_va[id]) goto err; - - rb_desc->nr_page_va++; } rb_desc = __next_ring_buffer_desc(rb_desc); } |