The patch titled
Subject: get_signal: hide_si_addr_tag_bits: fix the usage of uninitialized ksig
has been added to the -mm mm-nonmm-unstable branch. Its filename is
get_signal-hide_si_addr_tag_bits-fix-the-usage-of-uninitialized-ksig.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/get_signal-hide_si_addr_tag_bits-fix-the-usage-of-uninitialized-ksig.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: get_signal: hide_si_addr_tag_bits: fix the usage of uninitialized ksig
Date: Mon, 26 Feb 2024 17:56:50 +0100
ksig->ka and ksig->info are not initialized if get_signal() returns 0 or
if the caller is PF_USER_WORKER.
Check signr != 0 before SA_EXPOSE_TAGBITS and move the "out" label down.
The latter means that ksig->sig won't be initialized if a PF_USER_WORKER
thread gets a fatal signal but this is fine, PF_USER_WORKER's don't use
ksig. And there is nothing new, in this case ksig->ka and ksig-info are
not initialized anyway. Add a comment.
Link: https://lkml.kernel.org/r/20240226165650.GA20829@xxxxxxxxxx
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Peter Collingbourne <pcc@xxxxxxxxxx>
Cc: Wen Yang <wenyang.linux@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/signal.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
--- a/kernel/signal.c~get_signal-hide_si_addr_tag_bits-fix-the-usage-of-uninitialized-ksig
+++ a/kernel/signal.c
@@ -2881,8 +2881,9 @@ relock:
/*
* PF_USER_WORKER threads will catch and exit on fatal signals
- * themselves. They have cleanup that must be performed, so
- * we cannot call do_exit() on their behalf.
+ * themselves. They have cleanup that must be performed, so we
+ * cannot call do_exit() on their behalf. Note that ksig won't
+ * be properly initialized, PF_USER_WORKER's shouldn't use it.
*/
if (current->flags & PF_USER_WORKER)
goto out;
@@ -2894,12 +2895,12 @@ relock:
/* NOTREACHED */
}
spin_unlock_irq(&sighand->siglock);
-out:
+
ksig->sig = signr;
- if (!(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
+ if (signr && !(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
hide_si_addr_tag_bits(ksig);
-
+out:
return signr > 0;
}
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
get_signal-dont-abuse-ksig-infosi_signo-and-ksig-sig.patch
get_signal-hide_si_addr_tag_bits-fix-the-usage-of-uninitialized-ksig.patch
get_signal-dont-initialize-ksig-info-if-signal_group_exit-group_exec_task.patch
