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Subject[PATCH AUTOSEL 4.19 07/68] xsk: fix umem memory leak on cleanup
Date
From: Björn Töpel <bjorn.topel@intel.com>

[ Upstream commit 044175a06706d516aa42874bb44dbbfc3c4d20eb ]

When the umem is cleaned up, the task that created it might already be
gone. If the task was gone, the xdp_umem_release function did not free
the pages member of struct xdp_umem.

It turned out that the task lookup was not needed at all; The code was
a left-over when we moved from task accounting to user accounting [1].

This patch fixes the memory leak by removing the task lookup logic
completely.

[1] https://lore.kernel.org/netdev/20180131135356.19134-3-bjorn.topel@gmail.com/

Link: https://lore.kernel.org/netdev/c1cb2ca8-6a14-3980-8672-f3de0bb38dfd@suse.cz/
Fixes: c0c77d8fb787 ("xsk: add user memory registration support sockopt")
Reported-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>
---
include/net/xdp_sock.h | 1 -
net/xdp/xdp_umem.c | 19 +------------------
2 files changed, 1 insertion(+), 19 deletions(-)

diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index 7161856bcf9c..c2c10cc9ffa0 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -34,7 +34,6 @@ struct xdp_umem {
u32 headroom;
u32 chunk_size_nohr;
struct user_struct *user;
- struct pid *pid;
unsigned long address;
refcount_t users;
struct work_struct work;
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index bfe2dbea480b..a3b037fbfecd 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -152,9 +152,6 @@ static void xdp_umem_unaccount_pages(struct xdp_umem *umem)

static void xdp_umem_release(struct xdp_umem *umem)
{
- struct task_struct *task;
- struct mm_struct *mm;
-
xdp_umem_clear_dev(umem);

if (umem->fq) {
@@ -169,21 +166,10 @@ static void xdp_umem_release(struct xdp_umem *umem)

xdp_umem_unpin_pages(umem);

- task = get_pid_task(umem->pid, PIDTYPE_PID);
- put_pid(umem->pid);
- if (!task)
- goto out;
- mm = get_task_mm(task);
- put_task_struct(task);
- if (!mm)
- goto out;
-
- mmput(mm);
kfree(umem->pages);
umem->pages = NULL;

xdp_umem_unaccount_pages(umem);
-out:
kfree(umem);
}

@@ -312,7 +298,6 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
if (size_chk < 0)
return -EINVAL;

- umem->pid = get_task_pid(current, PIDTYPE_PID);
umem->address = (unsigned long)addr;
umem->props.chunk_mask = ~((u64)chunk_size - 1);
umem->props.size = size;
@@ -328,7 +313,7 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)

err = xdp_umem_account_pages(umem);
if (err)
- goto out;
+ return err;

err = xdp_umem_pin_pages(umem);
if (err)
@@ -347,8 +332,6 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)

out_account:
xdp_umem_unaccount_pages(umem);
-out:
- put_pid(umem->pid);
return err;
}

--
2.19.1
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