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author | Rich Felker <dalias@aerifal.cx> | 2011-03-24 14:18:00 -0400 |
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committer | Rich Felker <dalias@aerifal.cx> | 2011-03-24 14:18:00 -0400 |
commit | b470030f839a375e5030ec9d44903ef7581c15a2 (patch) | |
tree | 462b1df89a3ea45bcf50b9d0a844472576ed6585 /src/termios | |
parent | 095820016689dfdc9141f477a86de22054c86078 (diff) | |
download | musl-b470030f839a375e5030ec9d44903ef7581c15a2.tar.gz musl-b470030f839a375e5030ec9d44903ef7581c15a2.tar.bz2 musl-b470030f839a375e5030ec9d44903ef7581c15a2.tar.xz musl-b470030f839a375e5030ec9d44903ef7581c15a2.zip |
overhaul cancellation to fix resource leaks and dangerous behavior with signals
this commit addresses two issues:
1. a race condition, whereby a cancellation request occurring after a
syscall returned from kernelspace but before the subsequent
CANCELPT_END would cause cancellable resource-allocating syscalls
(like open) to leak resources.
2. signal handlers invoked while the thread was blocked at a
cancellation point behaved as if asynchronous cancellation mode wer in
effect, resulting in potentially dangerous state corruption if a
cancellation request occurs.
the glibc/nptl implementation of threads shares both of these issues.
with this commit, both are fixed. however, cancellation points
encountered in a signal handler will not be acted upon if the signal
was received while the thread was already at a cancellation point.
they will of course be acted upon after the signal handler returns, so
in real-world usage where signal handlers quickly return, it should
not be a problem. it's possible to solve this problem too by having
sigaction() wrap all signal handlers with a function that uses a
pthread_cleanup handler to catch cancellation, patch up the saved
context, and return into the cancellable function that will catch and
act upon the cancellation. however that would be a lot of complexity
for minimal if any benefit...
Diffstat (limited to 'src/termios')
-rw-r--r-- | src/termios/tcdrain.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/src/termios/tcdrain.c b/src/termios/tcdrain.c index 8e889b51..9ff1ecd5 100644 --- a/src/termios/tcdrain.c +++ b/src/termios/tcdrain.c @@ -7,6 +7,7 @@ int tcdrain(int fd) int ret; CANCELPT_BEGIN; ret = ioctl(fd, TCSBRK, 1); + CANCELPT_TRY; CANCELPT_END; return ret; } |