From f5178c41bb43444a6008150fe6094497135d07cb Mon Sep 17 00:00:00 2001 From: Jeongjun Park Date: Tue, 22 Apr 2025 20:30:25 +0900 Subject: tracing: Fix oob write in trace_seq_to_buffer() syzbot reported this bug: ================================================================== BUG: KASAN: slab-out-of-bounds in trace_seq_to_buffer kernel/trace/trace.c:1830 [inline] BUG: KASAN: slab-out-of-bounds in tracing_splice_read_pipe+0x6be/0xdd0 kernel/trace/trace.c:6822 Write of size 4507 at addr ffff888032b6b000 by task syz.2.320/7260 CPU: 1 UID: 0 PID: 7260 Comm: syz.2.320 Not tainted 6.15.0-rc1-syzkaller-00301-g3bde70a2c827 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xc3/0x670 mm/kasan/report.c:521 kasan_report+0xe0/0x110 mm/kasan/report.c:634 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0xef/0x1a0 mm/kasan/generic.c:189 __asan_memcpy+0x3c/0x60 mm/kasan/shadow.c:106 trace_seq_to_buffer kernel/trace/trace.c:1830 [inline] tracing_splice_read_pipe+0x6be/0xdd0 kernel/trace/trace.c:6822 .... ================================================================== It has been reported that trace_seq_to_buffer() tries to copy more data than PAGE_SIZE to buf. Therefore, to prevent this, we should use the smaller of trace_seq_used(&iter->seq) and PAGE_SIZE as an argument. Link: https://lore.kernel.org/20250422113026.13308-1-aha310510@gmail.com Reported-by: syzbot+c8cd2d2c412b868263fb@syzkaller.appspotmail.com Fixes: 3c56819b14b0 ("tracing: splice support for tracing_pipe") Suggested-by: Steven Rostedt Signed-off-by: Jeongjun Park Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'kernel/trace/trace.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 8ddf6b17215c..6d52dc108f00 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6821,13 +6821,14 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, /* Copy the data into the page, so we can start over. */ ret = trace_seq_to_buffer(&iter->seq, page_address(spd.pages[i]), - trace_seq_used(&iter->seq)); + min((size_t)trace_seq_used(&iter->seq), + PAGE_SIZE)); if (ret < 0) { __free_page(spd.pages[i]); break; } spd.partial[i].offset = 0; - spd.partial[i].len = trace_seq_used(&iter->seq); + spd.partial[i].len = ret; trace_seq_init(&iter->seq); } -- cgit v1.2.3 From 1be8e54a1e0f0a4bf70e3d65f94ca1738ee4f1f3 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 1 May 2025 15:19:09 -0400 Subject: tracing: Fix trace_adjust_address() when there is no modules in scratch area The function trace_adjust_address() is used to map addresses of modules stored in the persistent memory and are also loaded in the current boot to return the current address for the module. If there's only one module entry, it will simply use that, otherwise it performs a bsearch of the entry array to find the modules to offset with. The issue is if there are no modules in the array. The code does not account for that and ends up referencing the first element in the array which does not exist and causes a crash. If nr_entries is zero, exit out early as if this was a core kernel address. Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Link: https://lore.kernel.org/20250501151909.65910359@gandalf.local.home Fixes: 35a380ddbc653 ("tracing: Show last module text symbols in the stacktrace") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel/trace/trace.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 6d52dc108f00..5b8db27fb6ef 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6043,8 +6043,10 @@ unsigned long trace_adjust_address(struct trace_array *tr, unsigned long addr) tscratch = tr->scratch; /* if there is no tscrach, module_delta must be NULL. */ module_delta = READ_ONCE(tr->module_delta); - if (!module_delta || tscratch->entries[0].mod_addr > addr) + if (!module_delta || !tscratch->nr_entries || + tscratch->entries[0].mod_addr > addr) { return addr + tr->text_delta; + } /* Note that entries must be sorted. */ nr_entries = tscratch->nr_entries; -- cgit v1.2.3