[PATCH v6.1 1/2] uprobes: encapsulate preparation of uprobe args buffer

From: Vamsi Krishna Brahmajosyula
Date: Wed Nov 13 2024 - 09:54:29 EST

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In reply to: Vamsi Krishna Brahmajosyula: "[PATCH v6.1 2/2] uprobe: avoid out-of-bounds memory access of fetching args"
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From: Andrii Nakryiko <andrii@xxxxxxxxxx>

[ Upstream commit 3eaea21b4d27cff0017c20549aeb53034c58fc23 ]

Move the logic of fetching temporary per-CPU uprobe buffer and storing
uprobes args into it to a new helper function. Store data size as part
of this buffer, simplifying interfaces a bit, as now we only pass single
uprobe_cpu_buffer reference around, instead of pointer + dsize.

This logic was duplicated across uprobe_dispatcher and uretprobe_dispatcher,
and now will be centralized. All this is also in preparation to make
this uprobe_cpu_buffer handling logic optional in the next patch.

Link: https://lore.kernel.org/all/20240318181728.2795838-2-andrii@xxxxxxxxxx/
[Masami: update for v6.9-rc3 kernel]

Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Reviewed-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Stable-dep-of: 373b9338c972 ("uprobe: avoid out-of-bounds memory access of fetching args")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
Signed-off-by: Vamsi Krishna Brahmajosyula <vamsi-krishna.brahmajosyula@xxxxxxxxxxxx>
---
kernel/trace/trace_uprobe.c | 79 +++++++++++++++++++------------------
1 file changed, 41 insertions(+), 38 deletions(-)

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 127c78aec17d..e09eef65d32f 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -858,6 +858,7 @@ static const struct file_operations uprobe_profile_ops = {
struct uprobe_cpu_buffer {
struct mutex mutex;
void *buf;
+ int dsize;
};
static struct uprobe_cpu_buffer __percpu *uprobe_cpu_buffer;
static int uprobe_buffer_refcnt;
@@ -947,9 +948,26 @@ static void uprobe_buffer_put(struct uprobe_cpu_buffer *ucb)
mutex_unlock(&ucb->mutex);
}

+static struct uprobe_cpu_buffer *prepare_uprobe_buffer(struct trace_uprobe *tu,
+ struct pt_regs *regs)
+{
+ struct uprobe_cpu_buffer *ucb;
+ int dsize, esize;
+
+ esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
+ dsize = __get_data_size(&tu->tp, regs);
+
+ ucb = uprobe_buffer_get();
+ ucb->dsize = tu->tp.size + dsize;
+
+ store_trace_args(ucb->buf, &tu->tp, regs, esize, dsize);
+
+ return ucb;
+}
+
static void __uprobe_trace_func(struct trace_uprobe *tu,
unsigned long func, struct pt_regs *regs,
- struct uprobe_cpu_buffer *ucb, int dsize,
+ struct uprobe_cpu_buffer *ucb,
struct trace_event_file *trace_file)
{
struct uprobe_trace_entry_head *entry;
@@ -960,14 +978,14 @@ static void __uprobe_trace_func(struct trace_uprobe *tu,

WARN_ON(call != trace_file->event_call);

- if (WARN_ON_ONCE(tu->tp.size + dsize > PAGE_SIZE))
+ if (WARN_ON_ONCE(ucb->dsize > PAGE_SIZE))
return;

if (trace_trigger_soft_disabled(trace_file))
return;

esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
- size = esize + tu->tp.size + dsize;
+ size = esize + ucb->dsize;
entry = trace_event_buffer_reserve(&fbuffer, trace_file, size);
if (!entry)
return;
@@ -981,14 +999,14 @@ static void __uprobe_trace_func(struct trace_uprobe *tu,
data = DATAOF_TRACE_ENTRY(entry, false);
}

- memcpy(data, ucb->buf, tu->tp.size + dsize);
+ memcpy(data, ucb->buf, ucb->dsize);

trace_event_buffer_commit(&fbuffer);
}

/* uprobe handler */
static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs,
- struct uprobe_cpu_buffer *ucb, int dsize)
+ struct uprobe_cpu_buffer *ucb)
{
struct event_file_link *link;

@@ -997,7 +1015,7 @@ static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs,

rcu_read_lock();
trace_probe_for_each_link_rcu(link, &tu->tp)
- __uprobe_trace_func(tu, 0, regs, ucb, dsize, link->file);
+ __uprobe_trace_func(tu, 0, regs, ucb, link->file);
rcu_read_unlock();

return 0;
@@ -1005,13 +1023,13 @@ static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs,

static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
struct pt_regs *regs,
- struct uprobe_cpu_buffer *ucb, int dsize)
+ struct uprobe_cpu_buffer *ucb)
{
struct event_file_link *link;

rcu_read_lock();
trace_probe_for_each_link_rcu(link, &tu->tp)
- __uprobe_trace_func(tu, func, regs, ucb, dsize, link->file);
+ __uprobe_trace_func(tu, func, regs, ucb, link->file);
rcu_read_unlock();
}

@@ -1339,7 +1357,7 @@ static bool uprobe_perf_filter(struct uprobe_consumer *uc,

static void __uprobe_perf_func(struct trace_uprobe *tu,
unsigned long func, struct pt_regs *regs,
- struct uprobe_cpu_buffer *ucb, int dsize)
+ struct uprobe_cpu_buffer *ucb)
{
struct trace_event_call *call = trace_probe_event_call(&tu->tp);
struct uprobe_trace_entry_head *entry;
@@ -1360,7 +1378,7 @@ static void __uprobe_perf_func(struct trace_uprobe *tu,

esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));

- size = esize + tu->tp.size + dsize;
+ size = esize + ucb->dsize;
size = ALIGN(size + sizeof(u32), sizeof(u64)) - sizeof(u32);
if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large enough"))
return;
@@ -1383,13 +1401,10 @@ static void __uprobe_perf_func(struct trace_uprobe *tu,
data = DATAOF_TRACE_ENTRY(entry, false);
}

- memcpy(data, ucb->buf, tu->tp.size + dsize);
-
- if (size - esize > tu->tp.size + dsize) {
- int len = tu->tp.size + dsize;
+ memcpy(data, ucb->buf, ucb->dsize);

- memset(data + len, 0, size - esize - len);
- }
+ if (size - esize > ucb->dsize)
+ memset(data + ucb->dsize, 0, size - esize - ucb->dsize);

perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
head, NULL);
@@ -1399,21 +1414,21 @@ static void __uprobe_perf_func(struct trace_uprobe *tu,

/* uprobe profile handler */
static int uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs,
- struct uprobe_cpu_buffer *ucb, int dsize)
+ struct uprobe_cpu_buffer *ucb)
{
if (!uprobe_perf_filter(&tu->consumer, 0, current->mm))
return UPROBE_HANDLER_REMOVE;

if (!is_ret_probe(tu))
- __uprobe_perf_func(tu, 0, regs, ucb, dsize);
+ __uprobe_perf_func(tu, 0, regs, ucb);
return 0;
}

static void uretprobe_perf_func(struct trace_uprobe *tu, unsigned long func,
struct pt_regs *regs,
- struct uprobe_cpu_buffer *ucb, int dsize)
+ struct uprobe_cpu_buffer *ucb)
{
- __uprobe_perf_func(tu, func, regs, ucb, dsize);
+ __uprobe_perf_func(tu, func, regs, ucb);
}

int bpf_get_uprobe_info(const struct perf_event *event, u32 *fd_type,
@@ -1479,10 +1494,8 @@ static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
struct trace_uprobe *tu;
struct uprobe_dispatch_data udd;
struct uprobe_cpu_buffer *ucb;
- int dsize, esize;
int ret = 0;

-
tu = container_of(con, struct trace_uprobe, consumer);
tu->nhit++;

@@ -1494,18 +1507,14 @@ static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
if (WARN_ON_ONCE(!uprobe_cpu_buffer))
return 0;

- dsize = __get_data_size(&tu->tp, regs);
- esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
-
- ucb = uprobe_buffer_get();
- store_trace_args(ucb->buf, &tu->tp, regs, esize, dsize);
+ ucb = prepare_uprobe_buffer(tu, regs);

if (trace_probe_test_flag(&tu->tp, TP_FLAG_TRACE))
- ret |= uprobe_trace_func(tu, regs, ucb, dsize);
+ ret |= uprobe_trace_func(tu, regs, ucb);

#ifdef CONFIG_PERF_EVENTS
if (trace_probe_test_flag(&tu->tp, TP_FLAG_PROFILE))
- ret |= uprobe_perf_func(tu, regs, ucb, dsize);
+ ret |= uprobe_perf_func(tu, regs, ucb);
#endif
uprobe_buffer_put(ucb);
return ret;
@@ -1517,7 +1526,6 @@ static int uretprobe_dispatcher(struct uprobe_consumer *con,
struct trace_uprobe *tu;
struct uprobe_dispatch_data udd;
struct uprobe_cpu_buffer *ucb;
- int dsize, esize;

tu = container_of(con, struct trace_uprobe, consumer);

@@ -1529,18 +1537,13 @@ static int uretprobe_dispatcher(struct uprobe_consumer *con,
if (WARN_ON_ONCE(!uprobe_cpu_buffer))
return 0;

- dsize = __get_data_size(&tu->tp, regs);
- esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
-
- ucb = uprobe_buffer_get();
- store_trace_args(ucb->buf, &tu->tp, regs, esize, dsize);
-
+ ucb = prepare_uprobe_buffer(tu, regs);
if (trace_probe_test_flag(&tu->tp, TP_FLAG_TRACE))
- uretprobe_trace_func(tu, func, regs, ucb, dsize);
+ uretprobe_trace_func(tu, func, regs, ucb);

#ifdef CONFIG_PERF_EVENTS
if (trace_probe_test_flag(&tu->tp, TP_FLAG_PROFILE))
- uretprobe_perf_func(tu, func, regs, ucb, dsize);
+ uretprobe_perf_func(tu, func, regs, ucb);
#endif
uprobe_buffer_put(ucb);
return 0;
--
2.39.4

Next message: Ryusuke Konishi: "Re: [PATCH] nilfs2: fix a uaf in nilfs_find_entry"
Previous message: Christoph Hellwig: "Re: [PATCH v3 1/8] driver core: bus: add irq_get_affinity callback to bus_type"
In reply to: Vamsi Krishna Brahmajosyula: "[PATCH v6.1 2/2] uprobe: avoid out-of-bounds memory access of fetching args"
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