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Fix crashes caused by improper error handling on bpf_look/update/delete_elem #2623

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merged 2 commits into from
Jun 3, 2023
Merged

Fix crashes caused by improper error handling on bpf_look/update/delete_elem #2623

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6a9bbf3
Fix crashes caused by improper error handling for bpf_*_elem
May 24, 2023
41e485f
Add runtime test for parallel map accessing
May 25, 2023
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11 changes: 6 additions & 5 deletions src/bpftrace.cpp
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
#include <arpa/inet.h>
#include <cassert>
#include <cerrno>
#include <cstdio>
#include <cstring>
#include <ctime>
Expand Down Expand Up @@ -1531,7 +1532,7 @@ int BPFtrace::clear_map(IMap &map)
for (auto &key : keys)
{
int err = bpf_delete_elem(map.mapfd_, key.data());
if (err)
if (err && err != -ENOENT)
{
LOG(ERROR) << "failed to look up elem: " << err;
return -1;
Expand Down Expand Up @@ -1577,7 +1578,7 @@ int BPFtrace::zero_map(IMap &map)
{
int err = bpf_update_elem(map.mapfd_, key.data(), zero.data(), BPF_EXIST);

if (err)
if (err && err != -ENOENT)
{
LOG(ERROR) << "failed to look up elem: " << err;
return -1;
Expand Down Expand Up @@ -1616,7 +1617,7 @@ int BPFtrace::print_map(IMap &map, uint32_t top, uint32_t div)
value_size *= nvalues;
auto value = std::vector<uint8_t>(value_size);
int err = bpf_lookup_elem(map.mapfd_, key.data(), value.data());
if (err == -1)
if (err == -ENOENT)
{
// key was removed by the eBPF program during bpf_get_next_key() and bpf_lookup_elem(),
// let's skip this key
Expand Down Expand Up @@ -1702,7 +1703,7 @@ int BPFtrace::print_map_hist(IMap &map, uint32_t top, uint32_t div)
int value_size = map.type_.GetSize() * nvalues;
auto value = std::vector<uint8_t>(value_size);
int err = bpf_lookup_elem(map.mapfd_, key.data(), value.data());
if (err == -1)
if (err == -ENOENT)
{
// key was removed by the eBPF program during bpf_get_next_key() and bpf_lookup_elem(),
// let's skip this key
Expand Down Expand Up @@ -1781,7 +1782,7 @@ int BPFtrace::print_map_stats(IMap &map, uint32_t top, uint32_t div)
int value_size = map.type_.GetSize() * nvalues;
auto value = std::vector<uint8_t>(value_size);
int err = bpf_lookup_elem(map.mapfd_, key.data(), value.data());
if (err == -1)
if (err == -ENOENT)
{
// key was removed by the eBPF program during bpf_get_next_key() and bpf_lookup_elem(),
// let's skip this key
Expand Down
5 changes: 5 additions & 0 deletions tests/runtime/basic
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Original file line number Diff line number Diff line change
Expand Up @@ -196,6 +196,11 @@ PROG BEGIN { @x = 10; printf("%d", @x++); printf(" %d", ++@x); printf(" %d", @x-
EXPECT 10 12 12 10
TIMEOUT 1

NAME parallel map access
RUN {{BPFTRACE}} runtime/scripts/parallel_map_access.bt
EXPECT SUCCESS
TIMEOUT 2

NAME increment/decrement variable
PROG BEGIN { $x = 10; printf("%d", $x++); printf(" %d", ++$x); printf(" %d", $x--); printf(" %d\n", --$x); exit(); }
EXPECT 10 12 12 10
Expand Down
24 changes: 24 additions & 0 deletions tests/runtime/scripts/parallel_map_access.bt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,24 @@
// Regression testing the map's thread safety.
// Bpftrace shouldn't crash during map's print/clear/zero operations
// while delete is called at the same time.
//
// For more information, please refer to:
// https://github.com/iovisor/bpftrace/pull/2623

i:us:1 {
@data[rand % 100] = count();
if (rand % 5 == 0) {
delete(@data[rand % 10]);
}
}

i:ms:1 {
print(@data);
clear(@data);
zero(@data);
}

i:s:1 {
print("SUCCESS");
exit();
}