diff options
author | Will Dietz <w@wdtz.org> | 2018-09-18 17:11:12 -0500 |
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committer | Will Dietz <w@wdtz.org> | 2018-09-18 17:13:54 -0500 |
commit | 4305e7d5ecee69b82101c0cb273fddf23aa5c6e2 (patch) | |
tree | d937e1b270cf1753ee6ca00f7b719f8057dcb354 /pkgs/os-specific/linux/musl | |
parent | ea326dd4b52a57f812c72cba3d3d21dd9a343a85 (diff) |
musl: apply upstream fix for file locking race
Diffstat (limited to 'pkgs/os-specific/linux/musl')
-rw-r--r-- | pkgs/os-specific/linux/musl/default.nix | 3 | ||||
-rw-r--r-- | pkgs/os-specific/linux/musl/fix-file-locking-race.patch | 54 |
2 files changed, 57 insertions, 0 deletions
diff --git a/pkgs/os-specific/linux/musl/default.nix b/pkgs/os-specific/linux/musl/default.nix index f88e1850bad5b..ccabe97969a60 100644 --- a/pkgs/os-specific/linux/musl/default.nix +++ b/pkgs/os-specific/linux/musl/default.nix @@ -56,6 +56,9 @@ stdenv.mkDerivation rec { url = https://raw.githubusercontent.com/openwrt/openwrt/87606e25afac6776d1bbc67ed284434ec5a832b4/toolchain/musl/patches/300-relative.patch; sha256 = "0hfadrycb60sm6hb6by4ycgaqc9sgrhh42k39v8xpmcvdzxrsq2n"; }) + # Upstream bugfix, see: https://git.musl-libc.org/cgit/musl/commit/?id=0db393d3a77bb9f300a356c6a5484fc2dddb161d + # Explicitly flagged for inclusion by distributions using musl + ./fix-file-locking-race.patch ]; preConfigure = '' configureFlagsArray+=("--syslibdir=$out/lib") diff --git a/pkgs/os-specific/linux/musl/fix-file-locking-race.patch b/pkgs/os-specific/linux/musl/fix-file-locking-race.patch new file mode 100644 index 0000000000000..2ef91390a691f --- /dev/null +++ b/pkgs/os-specific/linux/musl/fix-file-locking-race.patch @@ -0,0 +1,54 @@ +From 0db393d3a77bb9f300a356c6a5484fc2dddb161d Mon Sep 17 00:00:00 2001 +From: Kaarle Ritvanen <kaarle.ritvanen@datakunkku.fi> +Date: Tue, 18 Sep 2018 10:03:27 +0300 +Subject: fix race condition in file locking + +The condition occurs when +- thread #1 is holding the lock +- thread #2 is waiting for it on __futexwait +- thread #1 is about to release the lock and performs a_swap +- thread #3 enters the __lockfile function and manages to grab the lock + before thread #1 calls __wake, resetting the MAYBE_WAITERS flag +- thread #1 calls __wake +- thread #2 wakes up but goes again to __futexwait as the lock is + held by thread #3 +- thread #3 releases the lock but does not call __wake as the + MAYBE_WAITERS flag is not set + +This condition results in thread #2 not being woken up. This patch fixes +the problem by making the woken up thread ensure that the flag is +properly set before going to sleep again. + +Mainainer's note: This fixes a regression introduced in commit +c21f750727515602a9e84f2a190ee8a0a2aeb2a1. +--- + src/stdio/__lockfile.c | 12 ++++++------ + 1 file changed, 6 insertions(+), 6 deletions(-) + +diff --git a/src/stdio/__lockfile.c b/src/stdio/__lockfile.c +index 2ff75d8a..0dcb2a42 100644 +--- a/src/stdio/__lockfile.c ++++ b/src/stdio/__lockfile.c +@@ -8,13 +8,13 @@ int __lockfile(FILE *f) + int owner = f->lock, tid = __pthread_self()->tid; + if ((owner & ~MAYBE_WAITERS) == tid) + return 0; +- for (;;) { +- owner = a_cas(&f->lock, 0, tid); +- if (!owner) return 1; +- if (a_cas(&f->lock, owner, owner|MAYBE_WAITERS)==owner) break; ++ owner = a_cas(&f->lock, 0, tid); ++ if (!owner) return 1; ++ while ((owner = a_cas(&f->lock, 0, tid|MAYBE_WAITERS))) { ++ if ((owner & MAYBE_WAITERS) || ++ a_cas(&f->lock, owner, owner|MAYBE_WAITERS)==owner) ++ __futexwait(&f->lock, owner|MAYBE_WAITERS, 1); + } +- while ((owner = a_cas(&f->lock, 0, tid|MAYBE_WAITERS))) +- __futexwait(&f->lock, owner, 1); + return 1; + } + +-- +cgit v1.2.1 + |