Re: [PATCH 0/5] kallsyms: make kallsym APIs more safe with scnprintf
On Sat, May 21, 2022 at 11:07:52PM -0700, Christoph Hellwig wrote: > On Fri, May 20, 2022 at 02:06:56PM +0530, Maninder Singh wrote: > > kallsyms functionality depends on KSYM_NAME_LEN directly. > > but if user passed array length lesser than it, sprintf > > can cause issues of buffer overflow attack. > > > > So changing *sprint* and *lookup* APIs in this patch set > > to have buffer size as an argument and replacing sprintf with > > scnprintf. > > This is still a pretty horrible API. Passing something like > a struct seq_buf seems like the much better API here. Also with > the amount of arguments and by reference passing it might be worth > to pass them as a structure while you're at it. Yeah, I agree. It really seems like seq_buf would be nicer. -- Kees Cook
Re: [PATCH 0/5] kallsyms: make kallsym APIs more safe with scnprintf
On Fri, May 20, 2022 at 02:06:56PM +0530, Maninder Singh wrote: > kallsyms functionality depends on KSYM_NAME_LEN directly. > but if user passed array length lesser than it, sprintf > can cause issues of buffer overflow attack. > > So changing *sprint* and *lookup* APIs in this patch set > to have buffer size as an argument and replacing sprintf with > scnprintf. This is still a pretty horrible API. Passing something like a struct seq_buf seems like the much better API here. Also with the amount of arguments and by reference passing it might be worth to pass them as a structure while you're at it.
[PATCH 0/5] kallsyms: make kallsym APIs more safe with scnprintf
kallsyms functionality depends on KSYM_NAME_LEN directly. but if user passed array length lesser than it, sprintf can cause issues of buffer overflow attack. So changing *sprint* and *lookup* APIs in this patch set to have buffer size as an argument and replacing sprintf with scnprintf. patch 1 and 2 can be clubbed, but then it will be difficult to review, so patch 1 changes prototype only and patch 2 includes passed argument usage. Patch 3 and patch 5 are bug fixes. Patch 1, 2 and 4 are changing prorotypes. Tried build and kallsyms test on ARM64 environment. APIs are called at multiple places. So build can be failed if updation missed at any place. lets see if autobot reports any build failure with any config combination. [ 12.247313] ps function_check [crash] [ 12.247906] pS function_check+0x4/0x40 [crash] [ 12.247999] pSb function_check+0x4/0x40 [crash df48d71893b7fb2688ac9739346449e89e8a76ca] [ 12.248092] pB function_check+0x4/0x40 [crash] [ 12.248190] pBb function_check+0x4/0x40 [crash df48d71893b7fb2688ac9739346449e89e8a76ca] ... [ 12.261175] Call trace: [ 12.261361] function_2+0x74/0x88 [crash df48d71893b7fb2688ac9739346449e89e8a76ca] [ 12.261859] function_1+0x10/0x1c [crash df48d71893b7fb2688ac9739346449e89e8a76ca] [ 12.262237] hello_init+0x24/0x34 [crash df48d71893b7fb2688ac9739346449e89e8a76ca] [ 12.262603] do_one_initcall+0x54/0x1c8 [ 12.262803] do_init_module+0x44/0x1d0 [ 12.262992] load_module+0x1688/0x19f0 [ 12.263179] __do_sys_init_module+0x1a0/0x210 [ 12.263387] __arm64_sys_init_module+0x1c/0x28 [ 12.263596] invoke_syscall+0x44/0x108 [ 12.263788] el0_svc_common.constprop.0+0x44/0xf0 [ 12.264014] do_el0_svc_compat+0x1c/0x50 [ 12.264209] el0_svc_compat+0x2c/0x88 [ 12.264397] el0t_32_sync_handler+0x90/0x140 [ 12.264600] el0t_32_sync+0x190/0x194 Maninder Singh, Onkarnath (5): kallsyms: pass buffer size in sprint_* APIs kallsyms: replace sprintf with scprintf arch:hexagon/powerpc: use KSYM_NAME_LEN as array size kallsyms: pass buffer size argument in *lookup* APIs kallsyms: remove unsed API lookup_symbol_attrs arch/hexagon/kernel/traps.c| 4 +- arch/powerpc/xmon/xmon.c | 6 +- arch/s390/lib/test_unwind.c| 2 +- drivers/scsi/fnic/fnic_trace.c | 8 +-- fs/proc/base.c | 2 +- include/linux/kallsyms.h | 34 +-- include/linux/module.h | 14 ++--- init/main.c| 2 +- kernel/debug/kdb/kdb_support.c | 2 +- kernel/kallsyms.c | 92 -- kernel/kprobes.c | 4 +- kernel/locking/lockdep.c | 8 +-- kernel/locking/lockdep_internals.h | 2 +- kernel/locking/lockdep_proc.c | 4 +- kernel/module/kallsyms.c | 36 ++-- kernel/trace/ftrace.c | 9 +-- kernel/trace/trace_kprobe.c| 2 +- kernel/trace/trace_output.c| 4 +- kernel/trace/trace_syscalls.c | 2 +- lib/vsprintf.c | 10 ++-- 20 files changed, 93 insertions(+), 154 deletions(-) -- 2.17.1
