** Description changed:
[Impact]
dtrace generates .c code in a predictable temporary file which makes it
susceptible to crashes. I've seen this happen in practice when rebuilding
libvirt/focal on a system with 48 cores. The race window is wide enough that
the crash is nearly 100% reproducible.
[Test Case]
- user@host:~$ cat foo/Makefile
+ user@host:~$ cat foo/Makefile
all: ../foo/foo.out foo.out
%.out:
- dtrace -o foo.out -G -s /dev/null
+ dtrace -o $@ -G -s /dev/null
clean:
rm -f foo.out
user@host:~$ cd foo
user@host:~/foo$ make
- dtrace -o foo.out -G -s /dev/null
+ dtrace -o ../foo/foo.out -G -s /dev/null
user@host:~/foo$ make clean
rm -f foo.out
user@host:~/foo$ make -j2
- dtrace -o foo.out -G -s /dev/null
+ dtrace -o ../foo/foo.out -G -s /dev/null
dtrace -o foo.out -G -s /dev/null
Traceback (most recent call last):
- File "/usr/bin/dtrace", line 455, in <module>
+ File "/usr/bin/dtrace", line 445, in <module>
sys.exit(main())
- File "/usr/bin/dtrace", line 440, in main
+ File "/usr/bin/dtrace", line 432, in main
os.remove(fname)
FileNotFoundError: [Errno 2] No such file or directory:
'foo.out.dtrace-temp.c'
- make: *** [Makefile:4: ../foo/foo.out] Error 1
+ make: *** [Makefile:4: foo.out] Error 1
[Fix]
https://sourceware.org/git/?p=systemtap.git;a=commit;h=0de9020c970bceda73e32bbd169c12e7579f21ec
[What could go wrong]
It is possible that a race still exists, but the fix should be an overall
improvement. Perhaps it is possible that a funky filename string could cause
UTF-8 encoding to fail resulting in a crash - though it would seem that such
input wouldn't be a valid path name and dtrace would crash anyway.
** Description changed:
[Impact]
dtrace generates .c code in a predictable temporary file which makes it
susceptible to crashes. I've seen this happen in practice when rebuilding
libvirt/focal on a system with 48 cores. The race window is wide enough that
the crash is nearly 100% reproducible.
[Test Case]
user@host:~$ cat foo/Makefile
all: ../foo/foo.out foo.out
%.out:
- dtrace -o $@ -G -s /dev/null
+ dtrace -o $@ -G -s /dev/null
clean:
- rm -f foo.out
+ rm -f foo.out
user@host:~$ cd foo
user@host:~/foo$ make
dtrace -o ../foo/foo.out -G -s /dev/null
user@host:~/foo$ make clean
rm -f foo.out
user@host:~/foo$ make -j2
dtrace -o ../foo/foo.out -G -s /dev/null
dtrace -o foo.out -G -s /dev/null
Traceback (most recent call last):
- File "/usr/bin/dtrace", line 445, in <module>
- sys.exit(main())
- File "/usr/bin/dtrace", line 432, in main
- os.remove(fname)
+ File "/usr/bin/dtrace", line 445, in <module>
+ sys.exit(main())
+ File "/usr/bin/dtrace", line 432, in main
+ os.remove(fname)
FileNotFoundError: [Errno 2] No such file or directory:
'foo.out.dtrace-temp.c'
make: *** [Makefile:4: foo.out] Error 1
[Fix]
https://sourceware.org/git/?p=systemtap.git;a=commit;h=0de9020c970bceda73e32bbd169c12e7579f21ec
[What could go wrong]
It is possible that a race still exists, but the fix should be an overall
improvement. Perhaps it is possible that a funky filename string could cause
UTF-8 encoding to fail resulting in a crash - though it would seem that such
input wouldn't be a valid path name and dtrace would crash anyway.
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https://bugs.launchpad.net/bugs/1962785
Title:
dtrace predictable temp file causes race
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