CVE-2023-53375

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/schedswitch/trigger # cat instances/foo/errorlog [ 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>] kmalloctrace+0x2a/0xa0 [<00000000b2938940>] tracinglogerr+0x277/0x2e0 [<000000004a0e1b07>] parseatom+0x966/0xb40 [<0000000023b24337>] parseexpr+0x5f3/0xdb0 [<00000000594ad074>] eventhisttriggerparse+0x27f8/0x3560 [<00000000293a9645>] triggerprocessregex+0x135/0x1a0 [<000000005c22b4f2>] eventtriggerwrite+0x87/0xf0 [<000000002cadc509>] vfswrite+0x162/0x670 [<0000000059c3b9be>] ksyswrite+0xca/0x170 [<00000000f1cddc00>] dosyscall64+0x3e/0xc0 [<00000000868ac68c>] entrySYSCALL64afterhwframe+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......... backtrace: [<000000006a747de5>] _kmalloc+0x4d/0x160 [<000000000039df5f>] tracinglogerr+0x29b/0x2e0 [<000000004a0e1b07>] parseatom+0x966/0xb40 [<0000000023b24337>] parseexpr+0x5f3/0xdb0 [<00000000594ad074>] eventhisttriggerparse+0x27f8/0x3560 [<00000000293a9645>] triggerprocessregex+0x135/0x1a0 [<000000005c22b4f2>] eventtriggerwrite+0x87/0xf0 [<000000002cadc509>] vfswrite+0x162/0x670 [<0000000059c3b9be>] ksyswrite+0xca/0x170 [<00000000f1cddc00>] dosyscall64+0x3e/0xc0 [<00000000868ac68c>] entrySYSCALL64afterhwframe+0x72/0xdc

The problem is that the error log needs to be freed when the instance is removed.