TLDRVuln - Cybersecurity Vulnerabilities Made Simple

In the Linux kernel, the following vulnerability has been resolved:

tracing: Free error logs of tracing instances

When a tracing instance is removed, the error messages that hold errors

that occurred in the instance needs to be freed. The following reports a

memory leak:

# cd /sys/kernel/tracing

# mkdir instances/foo

# echo 'hist:keys=x' > instances/foo/events/sched/sched_switch/trigger

# cat instances/foo/error_log

[ 117.404795] hist:sched:sched_switch: error: Couldn't find field

Command: hist:keys=x

# rmdir instances/foo

Then check for memory leaks:

# echo scan > /sys/kernel/debug/kmemleak

# cat /sys/kernel/debug/kmemleak

unreferenced object 0xffff88810d8ec700 (size 192):

comm "bash", pid 869, jiffies 4294950577 (age 215.752s)

hex dump (first 32 bytes):

60 dd 68 61 81 88 ff ff 60 dd 68 61 81 88 ff ff `.ha....`.ha....

a0 30 8c 83 ff ff ff ff 26 00 0a 00 00 00 00 00 .0......&.......

backtrace:

[<00000000dae26536>] kmalloc_trace+0x2a/0xa0

[<00000000b2938940>] tracing_log_err+0x277/0x2e0

[<000000004a0e1b07>] parse_atom+0x966/0xb40

[<0000000023b24337>] parse_expr+0x5f3/0xdb0

[<00000000594ad074>] event_hist_trigger_parse+0x27f8/0x3560

[<00000000293a9645>] trigger_process_regex+0x135/0x1a0

[<000000005c22b4f2>] event_trigger_write+0x87/0xf0

[<000000002cadc509>] vfs_write+0x162/0x670

[<0000000059c3b9be>] ksys_write+0xca/0x170

[<00000000f1cddc00>] do_syscall_64+0x3e/0xc0

[<00000000868ac68c>] entry_SYSCALL_64_after_hwframe+0x72/0xdc

unreferenced object 0xffff888170c35a00 (size 32):

comm "bash", pid 869, jiffies 4294950577 (age 215.752s)

hex dump (first 32 bytes):

0a 20 20 43 6f 6d 6d 61 6e 64 3a 20 68 69 73 74 . Command: hist

3a 6b 65 79 73 3d 78 0a 00 00 00 00 00 00 00 00 :keys=x.........