From ee9db1a9152e8757ce4d831ff9f4472ff5a57dad Mon Sep 17 00:00:00 2001 From: Zhixiong Chi Date: Tue, 5 Sep 2017 12:29:44 +0800 Subject: glibc: add ld.so locks in _libc_fork The patch in this Bugzilla entry was requested by a customer: https://sourceware.org/bugzilla/show_bug.cgi?id=4578 https://www.sourceware.org/bugzilla/show_bug.cgi?id=19282 If a thread happens to hold dl_load_lock and have r_state set to RT_ADD or RT_DELETE at the time another thread calls fork(), then the child exit code from fork (in nptl/sysdeps/unix/sysv/linux/fork.c in our case) re-initializes dl_load_lock but does not restore r_state to RT_CONSISTENT. If the child subsequently requires ld.so functionality before calling exec(), then the assertion will fire. The patch acquires dl_load_lock on entry to fork() and releases it on exit from the parent path. The child path is initialized as currently done. This is essentially pthreads_atfork, but forced to be first because the acquisition of dl_load_lock must happen before malloc_atfork is active to avoid a deadlock. The __libc_fork() code reset dl_load_lock, but it also needed to reset dl_load_write_lock. (From OE-Core rev: f2e586ebf59a9b7d5b216fc92aeb892069a4b0c1) Signed-off-by: Zhixiong Chi Signed-off-by: Ross Burton Signed-off-by: Richard Purdie --- ...bc-reset-dl-load-write-lock-after-forking.patch | 37 ++++++++++++++ .../0028-Bug-4578-add-ld.so-lock-while-fork.patch | 57 ++++++++++++++++++++++ meta/recipes-core/glibc/glibc_2.26.bb | 2 + 3 files changed, 96 insertions(+) create mode 100644 meta/recipes-core/glibc/glibc/0027-glibc-reset-dl-load-write-lock-after-forking.patch create mode 100644 meta/recipes-core/glibc/glibc/0028-Bug-4578-add-ld.so-lock-while-fork.patch (limited to 'meta/recipes-core/glibc') diff --git a/meta/recipes-core/glibc/glibc/0027-glibc-reset-dl-load-write-lock-after-forking.patch b/meta/recipes-core/glibc/glibc/0027-glibc-reset-dl-load-write-lock-after-forking.patch new file mode 100644 index 0000000000..777b253405 --- /dev/null +++ b/meta/recipes-core/glibc/glibc/0027-glibc-reset-dl-load-write-lock-after-forking.patch @@ -0,0 +1,37 @@ +From a6bb73d1cfd20a73fbbe6076008376fb87879d1b Mon Sep 17 00:00:00 2001 +From: Yuanjie Huang +Date: Thu, 18 Aug 2016 17:59:13 +0800 +Subject: [PATCH] reset dl_load_write_lock after forking + +The patch in this Bugzilla entry was requested by a customer: + + https://www.sourceware.org/bugzilla/show_bug.cgi?id=19282 + +The __libc_fork() code reset dl_load_lock, but it also needed to reset +dl_load_write_lock. The patch has not yet been integrated upstream. + +Upstream-Status: Pending [ Not Author See bugzilla] + +Signed-off-by: Damodar Sonone +Signed-off-by: Yuanjie Huang +--- + sysdeps/nptl/fork.c | 3 ++- + 1 file changed, 2 insertions(+), 1 deletion(-) + +diff --git a/sysdeps/nptl/fork.c b/sysdeps/nptl/fork.c +index 2b9ae4b..3d0b8da 100644 +--- a/sysdeps/nptl/fork.c ++++ b/sysdeps/nptl/fork.c +@@ -174,8 +174,9 @@ __libc_fork (void) + /* Reset locks in the I/O code. */ + _IO_list_resetlock (); + +- /* Reset the lock the dynamic loader uses to protect its data. */ ++ /* Reset the locks the dynamic loader uses to protect its data. */ + __rtld_lock_initialize (GL(dl_load_lock)); ++ __rtld_lock_initialize (GL(dl_load_write_lock)); + + /* Run the handlers registered for the child. */ + while (allp != NULL) +-- +1.9.1 diff --git a/meta/recipes-core/glibc/glibc/0028-Bug-4578-add-ld.so-lock-while-fork.patch b/meta/recipes-core/glibc/glibc/0028-Bug-4578-add-ld.so-lock-while-fork.patch new file mode 100644 index 0000000000..f76237a46e --- /dev/null +++ b/meta/recipes-core/glibc/glibc/0028-Bug-4578-add-ld.so-lock-while-fork.patch @@ -0,0 +1,57 @@ +The patch in this Bugzilla entry was requested by a customer: + https://sourceware.org/bugzilla/show_bug.cgi?id=4578 + +If a thread happens to hold dl_load_lock and have r_state set to RT_ADD or +RT_DELETE at the time another thread calls fork(), then the child exit code +from fork (in nptl/sysdeps/unix/sysv/linux/fork.c in our case) re-initializes +dl_load_lock but does not restore r_state to RT_CONSISTENT. If the child +subsequently requires ld.so functionality before calling exec(), then the +assertion will fire. + +The patch acquires dl_load_lock on entry to fork() and releases it on exit +from the parent path. The child path is initialized as currently done. +This is essentially pthreads_atfork, but forced to be first because the +acquisition of dl_load_lock must happen before malloc_atfork is active +to avoid a deadlock. +The patch has not yet been integrated upstream. + +Upstream-Status: Pending [ Not Author See bugzilla] + +Signed-off-by: Raghunath Lolur +Signed-off-by: Yuanjie Huang +Signed-off-by: Zhixiong Chi + +Index: git/sysdeps/nptl/fork.c +=================================================================== +--- git.orig/sysdeps/nptl/fork.c 2017-08-03 16:02:15.674704080 +0800 ++++ git/sysdeps/nptl/fork.c 2017-08-04 18:15:02.463362015 +0800 +@@ -25,6 +25,7 @@ + #include + #include + #include ++#include + #include + #include + #include +@@ -60,6 +61,10 @@ + but our current fork implementation is not. */ + bool multiple_threads = THREAD_GETMEM (THREAD_SELF, header.multiple_threads); + ++ /* grab ld.so lock BEFORE switching to malloc_atfork */ ++ __rtld_lock_lock_recursive (GL(dl_load_lock)); ++ __rtld_lock_lock_recursive (GL(dl_load_write_lock)); ++ + /* Run all the registered preparation handlers. In reverse order. + While doing this we build up a list of all the entries. */ + struct fork_handler *runp; +@@ -247,6 +252,10 @@ + + allp = allp->next; + } ++ ++ /* unlock ld.so last, because we locked it first */ ++ __rtld_lock_unlock_recursive (GL(dl_load_write_lock)); ++ __rtld_lock_unlock_recursive (GL(dl_load_lock)); + } + + return pid; diff --git a/meta/recipes-core/glibc/glibc_2.26.bb b/meta/recipes-core/glibc/glibc_2.26.bb index d453d8f9bf..135ec4fb16 100644 --- a/meta/recipes-core/glibc/glibc_2.26.bb +++ b/meta/recipes-core/glibc/glibc_2.26.bb @@ -41,6 +41,8 @@ SRC_URI = "${GLIBC_GIT_URI};branch=${SRCBRANCH};name=glibc \ file://0024-elf-dl-deps.c-Make-_dl_build_local_scope-breadth-fir.patch \ file://0025-locale-fix-hard-coded-reference-to-gcc-E.patch \ file://0026-assert-Suppress-pedantic-warning-caused-by-statement.patch \ + file://0027-glibc-reset-dl-load-write-lock-after-forking.patch \ + file://0028-Bug-4578-add-ld.so-lock-while-fork.patch \ " NATIVESDKFIXES ?= "" -- cgit v1.2.3-54-g00ecf