Daniel Xu 6fa6d28051 lib/strncpy_from_user.c: Mask out bytes after NUL terminator. ... do_strncpy_from_user() may copy some extra bytes after the NUL terminator into the destination buffer. This usually does not matter for normal string operations. However, when BPF programs key BPF maps with strings, this matters a lot. A BPF program may read strings from user memory by calling the bpf_probe_read_user_str() helper which eventually calls do_strncpy_from_user(). The program can then key a map with the destination buffer. BPF map keys are fixed-width and string-agnostic, meaning that map keys are treated as a set of bytes. The issue is when do_strncpy_from_user() overcopies bytes after the NUL terminator, it can result in seemingly identical strings occupying multiple slots in a BPF map. This behavior is subtle and totally unexpected by the user. This commit masks out the bytes following the NUL while preserving long-sized stride in the fast path. Fixes: 6ae08ae3de ("bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers") Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/21efc982b3e9f2f7b0379eed642294caaa0c27a7.1605642949.git.dxu@dxuuu.xyz		2020-11-19 11:56:16 -08:00
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blktrace.c
bpf_trace.c	lib/strncpy_from_user.c: Mask out bytes after NUL terminator.	2020-11-19 11:56:16 -08:00
bpf_trace.h
fgraph.c
ftrace.c
ftrace_internal.h
Kconfig
kprobe_event_gen_test.c
Makefile
power-traces.c
preemptirq_delay_test.c
ring_buffer.c	ring-buffer: Fix recursion protection transitions between interrupt context	2020-11-02 15:58:32 -05:00
ring_buffer_benchmark.c
rpm-traces.c
synth_event_gen_test.c
trace.c	tracing: Fix the checking of stackidx in __ftrace_trace_stack	2020-11-02 11:21:40 -05:00
trace.h	ftrace: Handle tracing when switching between context	2020-11-02 08:52:18 -05:00
trace_benchmark.c
trace_benchmark.h
trace_boot.c
trace_branch.c
trace_clock.c
trace_dynevent.c
trace_dynevent.h
trace_entries.h
trace_event_perf.c
trace_events.c
trace_events_filter.c
trace_events_filter_test.h
trace_events_hist.c
trace_events_inject.c
trace_events_synth.c	tracing: Make -ENOMEM the default error for parse_synth_field()	2020-11-02 15:58:32 -05:00
trace_events_trigger.c
trace_export.c
trace_functions.c
trace_functions_graph.c
trace_hwlat.c
trace_irqsoff.c
trace_kdb.c
trace_kprobe.c
trace_kprobe_selftest.c
trace_kprobe_selftest.h
trace_mmiotrace.c
trace_nop.c
trace_output.c
trace_output.h
trace_preemptirq.c
trace_printk.c
trace_probe.c
trace_probe.h
trace_probe_tmpl.h
trace_sched_switch.c
trace_sched_wakeup.c
trace_selftest.c	ftrace: Handle tracing when switching between context	2020-11-02 08:52:18 -05:00
trace_selftest_dynamic.c
trace_seq.c
trace_stack.c
trace_stat.c
trace_stat.h
trace_synth.h
trace_syscalls.c
trace_uprobe.c
tracing_map.c
tracing_map.h