[syzbot] [net?] KMSAN: kernel-infoleak in __skb_datagram_iter (2)

[syzbot] [net?] KMSAN: kernel-infoleak in __skb_datagram_iter (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    5bd7ef53ffe5 Merge tag 'pull-fixes' of git://git.kernel.or..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=13c1aee6e80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f3f069371247b697
dashboard link: https://syzkaller.appspot.com/bug?extid=34ad5fab48f7bf510349
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15555751e80000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10c93571e80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/cd1e7587b624/disk-5bd7ef53.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/62969c864f78/vmlinux-5bd7ef53.xz
kernel image: https://storage.googleapis.com/syzbot-assets/af66253a313c/bzImage-5bd7ef53.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+34ad5fab48f7bf510349@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: kernel-infoleak-after-free in instrument_copy_to_user include/linux/instrumented.h:114 [inline]
BUG: KMSAN: kernel-infoleak-after-free in copy_to_user_iter lib/iov_iter.c:24 [inline]
BUG: KMSAN: kernel-infoleak-after-free in iterate_ubuf include/linux/iov_iter.h:29 [inline]
BUG: KMSAN: kernel-infoleak-after-free in iterate_and_advance2 include/linux/iov_iter.h:245 [inline]
BUG: KMSAN: kernel-infoleak-after-free in iterate_and_advance include/linux/iov_iter.h:271 [inline]
BUG: KMSAN: kernel-infoleak-after-free in _copy_to_iter+0x364/0x2520 lib/iov_iter.c:186
 instrument_copy_to_user include/linux/instrumented.h:114 [inline]
 copy_to_user_iter lib/iov_iter.c:24 [inline]
 iterate_ubuf include/linux/iov_iter.h:29 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:245 [inline]
 iterate_and_advance include/linux/iov_iter.h:271 [inline]
 _copy_to_iter+0x364/0x2520 lib/iov_iter.c:186
 copy_to_iter include/linux/uio.h:197 [inline]
 simple_copy_to_iter+0x68/0xa0 net/core/datagram.c:532
 __skb_datagram_iter+0x123/0xdc0 net/core/datagram.c:420
 skb_copy_datagram_iter+0x5c/0x200 net/core/datagram.c:546
 skb_copy_datagram_msg include/linux/skbuff.h:3960 [inline]
 packet_recvmsg+0xd9c/0x2000 net/packet/af_packet.c:3482
 sock_recvmsg_nosec net/socket.c:1044 [inline]
 sock_recvmsg net/socket.c:1066 [inline]
 sock_read_iter+0x467/0x580 net/socket.c:1136
 call_read_iter include/linux/fs.h:2014 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x8f6/0xe00 fs/read_write.c:470
 ksys_read+0x20f/0x4c0 fs/read_write.c:613
 __do_sys_read fs/read_write.c:623 [inline]
 __se_sys_read fs/read_write.c:621 [inline]
 __x64_sys_read+0x93/0xd0 fs/read_write.c:621
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Uninit was stored to memory at:
 skb_put_data include/linux/skbuff.h:2622 [inline]
 netlink_to_full_skb net/netlink/af_netlink.c:181 [inline]
 __netlink_deliver_tap_skb net/netlink/af_netlink.c:298 [inline]
 __netlink_deliver_tap+0x5be/0xc90 net/netlink/af_netlink.c:325
 netlink_deliver_tap net/netlink/af_netlink.c:338 [inline]
 netlink_deliver_tap_kernel net/netlink/af_netlink.c:347 [inline]
 netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline]
 netlink_unicast+0x10f1/0x1250 net/netlink/af_netlink.c:1368
 netlink_sendmsg+0x1238/0x13d0 net/netlink/af_netlink.c:1910
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584
 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
 __sys_sendmsg net/socket.c:2667 [inline]
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Uninit was created at:
 free_pages_prepare mm/page_alloc.c:1087 [inline]
 free_unref_page_prepare+0xb0/0xa40 mm/page_alloc.c:2347
 free_unref_page_list+0xeb/0x1100 mm/page_alloc.c:2533
 release_pages+0x23d3/0x2410 mm/swap.c:1042
 free_pages_and_swap_cache+0xd9/0xf0 mm/swap_state.c:316
 tlb_batch_pages_flush mm/mmu_gather.c:98 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:293 [inline]
 tlb_flush_mmu+0x6f5/0x980 mm/mmu_gather.c:300
 tlb_finish_mmu+0x101/0x260 mm/mmu_gather.c:392
 exit_mmap+0x49e/0xd30 mm/mmap.c:3321
 __mmput+0x13f/0x530 kernel/fork.c:1349
 mmput+0x8a/0xa0 kernel/fork.c:1371
 exit_mm+0x1b8/0x360 kernel/exit.c:567
 do_exit+0xd57/0x4080 kernel/exit.c:858
 do_group_exit+0x2fd/0x390 kernel/exit.c:1021
 __do_sys_exit_group kernel/exit.c:1032 [inline]
 __se_sys_exit_group kernel/exit.c:1030 [inline]
 __x64_sys_exit_group+0x3c/0x50 kernel/exit.c:1030
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Bytes 3852-3903 of 3904 are uninitialized
Memory access of size 3904 starts at ffff88812ea1e000
Data copied to user address 0000000020003280

CPU: 1 PID: 5043 Comm: syz-executor297 Not tainted 6.7.0-rc5-syzkaller-00047-g5bd7ef53ffe5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
=====================================================


---
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Re: [syzbot] [PATCH] net: Fix kernel-infoleak in __skb_datagram_iter (2)

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org.

***

Subject: [PATCH] net: Fix kernel-infoleak in __skb_datagram_iter (2)
Author: ryasuoka@redhat.com

#syz test

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 27998f73183e..c7bf1c38b292 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2532,6 +2532,11 @@ static inline unsigned char
*skb_tail_pointer(const struct sk_buff *skb)
        return skb->head + skb->tail;
 }

+static inline unsigned int skb_tail_offset(const struct sk_buff *skb)
+{
+       return skb->tail;
+}
+
 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
 {
        skb->tail = skb->data - skb->head;
@@ -2549,6 +2554,11 @@ static inline unsigned char
*skb_tail_pointer(const struct sk_buff *skb)
        return skb->tail;
 }

+static inline unsigned int skb_tail_offset(const struct sk_buff *skb)
+{
+       return skb->tail - skb->head;
+}
+
 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
 {
        skb->tail = skb->data;
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index eb086b06d60d..f11bb308f1ed 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -167,7 +167,7 @@ static inline u32 netlink_group_mask(u32 group)
 static struct sk_buff *netlink_to_full_skb(const struct sk_buff *skb,
                                           gfp_t gfp_mask)
 {
-       unsigned int len = skb_end_offset(skb);
+       unsigned int len = skb_tail_offset(skb);
        struct sk_buff *new;

        new = alloc_skb(len, gfp_mask);

Re: [syzbot] Re: [PATCH] net: Fix kernel-infoleak in __skb_datagram_iter (2)

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org.

***

Subject: Re: [PATCH] net: Fix kernel-infoleak in __skb_datagram_iter (2)
Author: ryasuoka@redhat.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
master

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 2dde34c29203..540df9a6a9b3 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2542,6 +2542,11 @@ static inline unsigned char
*skb_tail_pointer(const struct sk_buff *skb)
        return skb->head + skb->tail;
 }

+static inline unsigned int skb_tail_offset(const struct sk_buff *skb)
+{
+       return skb->tail;
+}
+
 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
 {
        skb->tail = skb->data - skb->head;
@@ -2559,6 +2564,11 @@ static inline unsigned char
*skb_tail_pointer(const struct sk_buff *skb)
        return skb->tail;
 }

+static inline unsigned int skb_tail_offset(const struct sk_buff *skb)
+{
+       return skb->tail - skb->head;
+}
+
 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
 {
        skb->tail = skb->data;
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 9c962347cf85..d1b8e02c7e44 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -167,7 +167,7 @@ static inline u32 netlink_group_mask(u32 group)
 static struct sk_buff *netlink_to_full_skb(const struct sk_buff *skb,
                                           gfp_t gfp_mask)
 {
-       unsigned int len = skb_end_offset(skb);
+       unsigned int len = skb_tail_offset(skb);
        struct sk_buff *new;

        new = alloc_skb(len, gfp_mask);

Re: [syzbot] Re: [PATCH] net: Fix kernel-infoleak in __skb_datagram_iter (2)

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org.

***

Subject: Re: [PATCH] net: Fix kernel-infoleak in __skb_datagram_iter (2)
Author: ryasuoka@redhat.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
9f8413c4a66f

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 27998f73183e..c7bf1c38b292 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2532,6 +2532,11 @@ static inline unsigned char
*skb_tail_pointer(const struct sk_buff *skb)
  return skb->head + skb->tail;
 }

+static inline unsigned int skb_tail_offset(const struct sk_buff *skb)
+{
+ return skb->tail;
+}
+
 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
 {
  skb->tail = skb->data - skb->head;
@@ -2549,6 +2554,11 @@ static inline unsigned char
*skb_tail_pointer(const struct sk_buff *skb)
  return skb->tail;
 }

+static inline unsigned int skb_tail_offset(const struct sk_buff *skb)
+{
+ return skb->tail - skb->head;
+}
+
 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
 {
  skb->tail = skb->data;
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index eb086b06d60d..f11bb308f1ed 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -167,7 +167,7 @@ static inline u32 netlink_group_mask(u32 group)
 static struct sk_buff *netlink_to_full_skb(const struct sk_buff *skb,
     gfp_t gfp_mask)
 {
- unsigned int len = skb_end_offset(skb);
+ unsigned int len = skb_tail_offset(skb);
  struct sk_buff *new;

  new = alloc_skb(len, gfp_mask);

Re: [syzbot] [PATCH net] netlink: Fix kernel-infoleak in __skb_datagram_iter()

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org.

***

Subject: [PATCH net] netlink: Fix kernel-infoleak in __skb_datagram_iter()
Author: ryasuoka@redhat.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 5bd7ef53ffe5

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index eb086b06d60d..8277399d19b3 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -167,7 +167,7 @@ static inline u32 netlink_group_mask(u32 group)
 static struct sk_buff *netlink_to_full_skb(const struct sk_buff *skb,
                                           gfp_t gfp_mask)
 {
-       unsigned int len = skb_end_offset(skb);
+       unsigned int len = skb->len;
        struct sk_buff *new;

        new = alloc_skb(len, gfp_mask);

Re: [syzbot] [PATCH net] netlink: Fix kernel-infoleak in __skb_datagram_iter()

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org.

***

Subject: [PATCH net] netlink: Fix kernel-infoleak in __skb_datagram_iter()
Author: ryasuoka@redhat.com

#syz test

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 9c962347cf85..ff315351269f 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -167,7 +167,7 @@ static inline u32 netlink_group_mask(u32 group)
 static struct sk_buff *netlink_to_full_skb(const struct sk_buff *skb,
                                           gfp_t gfp_mask)
 {
-       unsigned int len = skb_end_offset(skb);
+       unsigned int len = skb->len;
        struct sk_buff *new;

        new = alloc_skb(len, gfp_mask);

Re: [syzbot] Test for 34ad5fab48f7bf510349

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org.

***

Subject: Test for 34ad5fab48f7bf510349
Author: syoshida@redhat.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 5bd7ef53ffe5ca580e93e74eb8c81ed191ddc4bd

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 9c962347cf85..c9ad41bce426 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -167,7 +167,8 @@ static inline u32 netlink_group_mask(u32 group)
 static struct sk_buff *netlink_to_full_skb(const struct sk_buff *skb,
 					   gfp_t gfp_mask)
 {
-	unsigned int len = skb_end_offset(skb);
+	//unsigned int len = skb_end_offset(skb);
+	unsigned int len = skb->len;
 	struct sk_buff *new;
 
 	new = alloc_skb(len, gfp_mask);

Re: [syzbot] [PATCH net] netlink: Fix kernel-infoleak in __skb_datagram_iter()

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org.

***

Subject: [PATCH net] netlink: Fix kernel-infoleak in __skb_datagram_iter()
Author: ryasuoka@redhat.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 5bd7ef53ffe5ca580e93e74eb8c81ed191ddc4bd

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index eb086b06d60d..8277399d19b3 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -167,7 +167,7 @@ static inline u32 netlink_group_mask(u32 group)
 static struct sk_buff *netlink_to_full_skb(const struct sk_buff *skb,
                                           gfp_t gfp_mask)
 {
-       unsigned int len = skb_end_offset(skb);
+       unsigned int len = skb->len;
        struct sk_buff *new;

        new = alloc_skb(len, gfp_mask);