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[v2,1/1] af_unix: Fix memory leak in unix_dgram_sendmsg()

Message ID 20250225021457.1824-1-ahuang12@lenovo.com (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series [v2,1/1] af_unix: Fix memory leak in unix_dgram_sendmsg() | expand

Checks

Context Check Description
netdev/series_format warning Single patches do not need cover letters; Target tree name not specified in the subject
netdev/tree_selection success Guessed tree name to be net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 6 of 6 maintainers
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 11 this patch: 11
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 7 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2025-02-25--15-00 (tests: 895)

Commit Message

Adrian Huang Feb. 25, 2025, 2:14 a.m. UTC 
From: Adrian Huang <ahuang12@lenovo.com>

After running the 'sendmsg02' program of Linux Test Project (LTP),
kmemleak reports the following memory leak:

  # cat /sys/kernel/debug/kmemleak
  unreferenced object 0xffff888243866800 (size 2048):
    comm "sendmsg02", pid 67, jiffies 4294903166
    hex dump (first 32 bytes):
      00 00 00 00 00 00 00 00 5e 00 00 00 00 00 00 00  ........^.......
      01 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00  ...@............
    backtrace (crc 7e96a3f2):
      kmemleak_alloc+0x56/0x90
      kmem_cache_alloc_noprof+0x209/0x450
      sk_prot_alloc.constprop.0+0x60/0x160
      sk_alloc+0x32/0xc0
      unix_create1+0x67/0x2b0
      unix_create+0x47/0xa0
      __sock_create+0x12e/0x200
      __sys_socket+0x6d/0x100
      __x64_sys_socket+0x1b/0x30
      x64_sys_call+0x7e1/0x2140
      do_syscall_64+0x54/0x110
      entry_SYSCALL_64_after_hwframe+0x76/0x7e

Commit 689c398885cc ("af_unix: Defer sock_put() to clean up path in
unix_dgram_sendmsg().") defers sock_put() in the error handling path.
However, it fails to account for the condition 'msg->msg_namelen != 0',
resulting in a memory leak when the code jumps to the 'lookup' label.

Fix issue by calling sock_put() if 'msg->msg_namelen != 0' is met.

Fixes: 689c398885cc ("af_unix: Defer sock_put() to clean up path in unix_dgram_sendmsg().")
Signed-off-by: Adrian Huang <ahuang12@lenovo.com>
---
Changelog v2:
 - Per Kuniyuki's suggestion: Remove 'else' statement

---
 net/unix/af_unix.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Joe Damato Feb. 25, 2025, 3:02 a.m. UTC | #1 
On Tue, Feb 25, 2025 at 10:14:57AM +0800, Adrian Huang wrote:
> From: Adrian Huang <ahuang12@lenovo.com>
> 
> After running the 'sendmsg02' program of Linux Test Project (LTP),
> kmemleak reports the following memory leak:
> 
>   # cat /sys/kernel/debug/kmemleak
>   unreferenced object 0xffff888243866800 (size 2048):
>     comm "sendmsg02", pid 67, jiffies 4294903166
>     hex dump (first 32 bytes):
>       00 00 00 00 00 00 00 00 5e 00 00 00 00 00 00 00  ........^.......
>       01 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00  ...@............
>     backtrace (crc 7e96a3f2):
>       kmemleak_alloc+0x56/0x90
>       kmem_cache_alloc_noprof+0x209/0x450
>       sk_prot_alloc.constprop.0+0x60/0x160
>       sk_alloc+0x32/0xc0
>       unix_create1+0x67/0x2b0
>       unix_create+0x47/0xa0
>       __sock_create+0x12e/0x200
>       __sys_socket+0x6d/0x100
>       __x64_sys_socket+0x1b/0x30
>       x64_sys_call+0x7e1/0x2140
>       do_syscall_64+0x54/0x110
>       entry_SYSCALL_64_after_hwframe+0x76/0x7e
> 
> Commit 689c398885cc ("af_unix: Defer sock_put() to clean up path in
> unix_dgram_sendmsg().") defers sock_put() in the error handling path.
> However, it fails to account for the condition 'msg->msg_namelen != 0',
> resulting in a memory leak when the code jumps to the 'lookup' label.
> 
> Fix issue by calling sock_put() if 'msg->msg_namelen != 0' is met.
> 
> Fixes: 689c398885cc ("af_unix: Defer sock_put() to clean up path in unix_dgram_sendmsg().")
> Signed-off-by: Adrian Huang <ahuang12@lenovo.com>
> ---
> Changelog v2:
>  - Per Kuniyuki's suggestion: Remove 'else' statement

FYI according to netdev rules you should wait at least 24 hours
between repostings:

https://docs.kernel.org/process/maintainer-netdev.html#resending-after-review

That said:

Acked-by: Joe Damato <jdamato@fastly.com>
Kuniyuki Iwashima Feb. 25, 2025, 7:09 p.m. UTC | #2 
From: Adrian Huang <adrianhuang0701@gmail.com>
Date: Tue, 25 Feb 2025 10:14:57 +0800
> From: Adrian Huang <ahuang12@lenovo.com>
> 
> After running the 'sendmsg02' program of Linux Test Project (LTP),
> kmemleak reports the following memory leak:
> 
>   # cat /sys/kernel/debug/kmemleak
>   unreferenced object 0xffff888243866800 (size 2048):
>     comm "sendmsg02", pid 67, jiffies 4294903166
>     hex dump (first 32 bytes):
>       00 00 00 00 00 00 00 00 5e 00 00 00 00 00 00 00  ........^.......
>       01 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00  ...@............
>     backtrace (crc 7e96a3f2):
>       kmemleak_alloc+0x56/0x90
>       kmem_cache_alloc_noprof+0x209/0x450
>       sk_prot_alloc.constprop.0+0x60/0x160
>       sk_alloc+0x32/0xc0
>       unix_create1+0x67/0x2b0
>       unix_create+0x47/0xa0
>       __sock_create+0x12e/0x200
>       __sys_socket+0x6d/0x100
>       __x64_sys_socket+0x1b/0x30
>       x64_sys_call+0x7e1/0x2140
>       do_syscall_64+0x54/0x110
>       entry_SYSCALL_64_after_hwframe+0x76/0x7e
> 
> Commit 689c398885cc ("af_unix: Defer sock_put() to clean up path in
> unix_dgram_sendmsg().") defers sock_put() in the error handling path.
> However, it fails to account for the condition 'msg->msg_namelen != 0',
> resulting in a memory leak when the code jumps to the 'lookup' label.
> 
> Fix issue by calling sock_put() if 'msg->msg_namelen != 0' is met.
> 
> Fixes: 689c398885cc ("af_unix: Defer sock_put() to clean up path in unix_dgram_sendmsg().")
> Signed-off-by: Adrian Huang <ahuang12@lenovo.com>

Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>

Thanks!
diff mbox series

Patch

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 34945de1fb1f..f0e613d97664 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2102,6 +2102,7 @@  static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 			goto out_sock_put;
 		}
 
+		sock_put(other);
 		goto lookup;
 	}