Patch "tls: fix lockless read of strp->msg_ready in ->poll" has been added to the 6.8-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    tls: fix lockless read of strp->msg_ready in ->poll

to the 6.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tls-fix-lockless-read-of-strp-msg_ready-in-poll.patch
and it can be found in the queue-6.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 43877813802f2733195713c3e90c18b4d9a21fe8
Author: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>
Date:   Wed Apr 24 12:25:47 2024 +0200

    tls: fix lockless read of strp->msg_ready in ->poll
    
    [ Upstream commit 0844370f8945086eb9335739d10205dcea8d707b ]
    
    tls_sk_poll is called without locking the socket, and needs to read
    strp->msg_ready (via tls_strp_msg_ready). Convert msg_ready to a bool
    and use READ_ONCE/WRITE_ONCE where needed. The remaining reads are
    only performed when the socket is locked.
    
    Fixes: 121dca784fc0 ("tls: suppress wakeups unless we have a full record")
    Signed-off-by: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/0b7ee062319037cf86af6b317b3d72f7bfcd2e97.1713797701.git.sd@xxxxxxxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/include/net/tls.h b/include/net/tls.h
index 340ad43971e47..33f657d3c0510 100644
--- a/include/net/tls.h
+++ b/include/net/tls.h
@@ -111,7 +111,8 @@ struct tls_strparser {
 	u32 stopped : 1;
 	u32 copy_mode : 1;
 	u32 mixed_decrypted : 1;
-	u32 msg_ready : 1;
+
+	bool msg_ready;
 
 	struct strp_msg stm;
 
diff --git a/net/tls/tls.h b/net/tls/tls.h
index 762f424ff2d59..e5e47452308ab 100644
--- a/net/tls/tls.h
+++ b/net/tls/tls.h
@@ -215,7 +215,7 @@ static inline struct sk_buff *tls_strp_msg(struct tls_sw_context_rx *ctx)
 
 static inline bool tls_strp_msg_ready(struct tls_sw_context_rx *ctx)
 {
-	return ctx->strp.msg_ready;
+	return READ_ONCE(ctx->strp.msg_ready);
 }
 
 static inline bool tls_strp_msg_mixed_decrypted(struct tls_sw_context_rx *ctx)
diff --git a/net/tls/tls_strp.c b/net/tls/tls_strp.c
index ca1e0e198ceb4..5df08d848b5c9 100644
--- a/net/tls/tls_strp.c
+++ b/net/tls/tls_strp.c
@@ -360,7 +360,7 @@ static int tls_strp_copyin(read_descriptor_t *desc, struct sk_buff *in_skb,
 	if (strp->stm.full_len && strp->stm.full_len == skb->len) {
 		desc->count = 0;
 
-		strp->msg_ready = 1;
+		WRITE_ONCE(strp->msg_ready, 1);
 		tls_rx_msg_ready(strp);
 	}
 
@@ -528,7 +528,7 @@ static int tls_strp_read_sock(struct tls_strparser *strp)
 	if (!tls_strp_check_queue_ok(strp))
 		return tls_strp_read_copy(strp, false);
 
-	strp->msg_ready = 1;
+	WRITE_ONCE(strp->msg_ready, 1);
 	tls_rx_msg_ready(strp);
 
 	return 0;
@@ -580,7 +580,7 @@ void tls_strp_msg_done(struct tls_strparser *strp)
 	else
 		tls_strp_flush_anchor_copy(strp);
 
-	strp->msg_ready = 0;
+	WRITE_ONCE(strp->msg_ready, 0);
 	memset(&strp->stm, 0, sizeof(strp->stm));
 
 	tls_strp_check_rcv(strp);