* Forwarded: Re: [syzbot] [bpf?] [net?] BUG: sleeping function called from invalid context in sock_map_delete_elem
2025-08-27 23:56 [syzbot] [bpf?] [net?] BUG: sleeping function called from invalid context in sock_map_delete_elem syzbot
@ 2025-10-01 18:26 ` syzbot
2025-10-09 21:26 ` Forwarded: " syzbot
` (3 subsequent siblings)
4 siblings, 0 replies; 8+ messages in thread
From: syzbot @ 2025-10-01 18:26 UTC (permalink / raw)
To: linux-kernel, syzkaller-bugs
For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.
***
Subject: Re: [syzbot] [bpf?] [net?] BUG: sleeping function called from invalid context in sock_map_delete_elem
Author: chandna.linuxkernel@gmail.com
#syz test
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -1368,7 +1368,7 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
- struct bpf_test_timer t = { NO_PREEMPT };
+ struct bpf_test_timer t = { NO_MIGRATE };
u32 size = kattr->test.data_size_in;
struct bpf_flow_dissector ctx = {};
u32 repeat = kattr->test.repeat;
--
^ permalink raw reply [flat|nested] 8+ messages in thread* Forwarded: Re: [bpf?] [net?] BUG: sleeping function called from invalid context in sock_map_delete_elem
2025-08-27 23:56 [syzbot] [bpf?] [net?] BUG: sleeping function called from invalid context in sock_map_delete_elem syzbot
2025-10-01 18:26 ` Forwarded: " syzbot
@ 2025-10-09 21:26 ` syzbot
2025-10-09 22:28 ` [PATCH] bpf: avoid sleeping in invalid context during sock_map_delete_elem path Brahmajit Das
` (2 subsequent siblings)
4 siblings, 0 replies; 8+ messages in thread
From: syzbot @ 2025-10-09 21:26 UTC (permalink / raw)
To: linux-kernel, syzkaller-bugs
For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.
***
Subject: Re: [bpf?] [net?] BUG: sleeping function called from invalid context in sock_map_delete_elem
Author: listout@listout.xyz
#syz test
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -38,10 +38,7 @@ static void bpf_test_timer_enter(struct bpf_test_timer *t)
__acquires(rcu)
{
rcu_read_lock();
- if (t->mode == NO_PREEMPT)
- preempt_disable();
- else
- migrate_disable();
+ migrate_disable();
t->time_start = ktime_get_ns();
}
@@ -51,10 +48,7 @@ static void bpf_test_timer_leave(struct bpf_test_timer *t)
{
t->time_start = 0;
- if (t->mode == NO_PREEMPT)
- preempt_enable();
- else
- migrate_enable();
+ migrate_enable();
rcu_read_unlock();
}
--
Regards,
listout
^ permalink raw reply [flat|nested] 8+ messages in thread* [PATCH] bpf: avoid sleeping in invalid context during sock_map_delete_elem path
2025-08-27 23:56 [syzbot] [bpf?] [net?] BUG: sleeping function called from invalid context in sock_map_delete_elem syzbot
2025-10-01 18:26 ` Forwarded: " syzbot
2025-10-09 21:26 ` Forwarded: " syzbot
@ 2025-10-09 22:28 ` Brahmajit Das
2025-10-09 22:38 ` Alexei Starovoitov
2025-10-09 23:29 ` [syzbot] [bpf?] [net?] BUG: sleeping function called from invalid context in sock_map_delete_elem syzbot
2025-10-13 16:29 ` Forwarded: [PATCH] bpf: avoid sleeping in invalid context during sock_map_delete_elem path syzbot
2025-10-13 17:11 ` [PATCH v2] " Brahmajit Das
4 siblings, 2 replies; 8+ messages in thread
From: Brahmajit Das @ 2025-10-09 22:28 UTC (permalink / raw)
To: syzbot+1f1fbecb9413cdbfbef8
Cc: ast, listout, bpf, linux-kernel, netdev, syzkaller-bugs,
yonghong.song
#syz test
The syzkaller report exposed a BUG: “sleeping function called from
invalid context” in sock_map_delete_elem, which happens when
`bpf_test_timer_enter()` disables preemption but the delete path later
invokes a sleeping function while still in that context. Specifically:
- The crash trace shows `bpf_test_timer_enter()` acquiring a
preempt_disable path (via t->mode == NO_PREEMPT), but the symmetric
release path always calls migrate_enable(), mismatching the earlier
disable.
- As a result, preemption remains disabled across the
sock_map_delete_elem path, leading to a sleeping call under an invalid
context. :contentReference[oaicite:0]{index=0}
To fix this, normalize the disable/enable pairing: always use
migrate_disable()/migrate_enable() regardless of t->mode. This ensures
that we never remain with preemption disabled unintentionally when
entering the delete path, and avoids invalid-context sleeping.
Reported-by: syzbot+1f1fbecb9413cdbfbef8@syzkaller.appspotmail.com
Signed-off-by: Brahmajit Das <listout@listout.xyz>
---
net/bpf/test_run.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index dfb03ee0bb62..07ffe7d92c1c 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -38,10 +38,7 @@ static void bpf_test_timer_enter(struct bpf_test_timer *t)
__acquires(rcu)
{
rcu_read_lock();
- if (t->mode == NO_PREEMPT)
- preempt_disable();
- else
- migrate_disable();
+ migrate_disable();
t->time_start = ktime_get_ns();
}
@@ -51,10 +48,7 @@ static void bpf_test_timer_leave(struct bpf_test_timer *t)
{
t->time_start = 0;
- if (t->mode == NO_PREEMPT)
- preempt_enable();
- else
- migrate_enable();
+ migrate_enable();
rcu_read_unlock();
}
--
2.51.0
^ permalink raw reply related [flat|nested] 8+ messages in thread* Re: [PATCH] bpf: avoid sleeping in invalid context during sock_map_delete_elem path
2025-10-09 22:28 ` [PATCH] bpf: avoid sleeping in invalid context during sock_map_delete_elem path Brahmajit Das
@ 2025-10-09 22:38 ` Alexei Starovoitov
2025-10-09 23:29 ` [syzbot] [bpf?] [net?] BUG: sleeping function called from invalid context in sock_map_delete_elem syzbot
1 sibling, 0 replies; 8+ messages in thread
From: Alexei Starovoitov @ 2025-10-09 22:38 UTC (permalink / raw)
To: Brahmajit Das
Cc: syzbot+1f1fbecb9413cdbfbef8, Alexei Starovoitov, bpf, LKML,
Network Development, syzkaller-bugs, Yonghong Song
On Thu, Oct 9, 2025 at 3:29 PM Brahmajit Das <listout@listout.xyz> wrote:
>
> #syz test
>
> The syzkaller report exposed a BUG: “sleeping function called from
> invalid context” in sock_map_delete_elem, which happens when
> `bpf_test_timer_enter()` disables preemption but the delete path later
> invokes a sleeping function while still in that context. Specifically:
>
> - The crash trace shows `bpf_test_timer_enter()` acquiring a
> preempt_disable path (via t->mode == NO_PREEMPT), but the symmetric
> release path always calls migrate_enable(), mismatching the earlier
> disable.
> - As a result, preemption remains disabled across the
> sock_map_delete_elem path, leading to a sleeping call under an invalid
> context. :contentReference[oaicite:0]{index=0}
>
> To fix this, normalize the disable/enable pairing: always use
> migrate_disable()/migrate_enable() regardless of t->mode. This ensures
> that we never remain with preemption disabled unintentionally when
> entering the delete path, and avoids invalid-context sleeping.
>
> Reported-by: syzbot+1f1fbecb9413cdbfbef8@syzkaller.appspotmail.com
> Signed-off-by: Brahmajit Das <listout@listout.xyz>
> ---
> net/bpf/test_run.c | 10 ++--------
> 1 file changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> index dfb03ee0bb62..07ffe7d92c1c 100644
> --- a/net/bpf/test_run.c
> +++ b/net/bpf/test_run.c
> @@ -38,10 +38,7 @@ static void bpf_test_timer_enter(struct bpf_test_timer *t)
> __acquires(rcu)
> {
> rcu_read_lock();
> - if (t->mode == NO_PREEMPT)
> - preempt_disable();
> - else
> - migrate_disable();
> + migrate_disable();
pls search previous thread on this subject.
pw-bot: cr
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [syzbot] [bpf?] [net?] BUG: sleeping function called from invalid context in sock_map_delete_elem
2025-10-09 22:28 ` [PATCH] bpf: avoid sleeping in invalid context during sock_map_delete_elem path Brahmajit Das
2025-10-09 22:38 ` Alexei Starovoitov
@ 2025-10-09 23:29 ` syzbot
1 sibling, 0 replies; 8+ messages in thread
From: syzbot @ 2025-10-09 23:29 UTC (permalink / raw)
To: ast, bpf, linux-kernel, listout, netdev, syzkaller-bugs,
yonghong.song
Hello,
syzbot has tested the proposed patch and the reproducer did not trigger any issue:
Reported-by: syzbot+1f1fbecb9413cdbfbef8@syzkaller.appspotmail.com
Tested-by: syzbot+1f1fbecb9413cdbfbef8@syzkaller.appspotmail.com
Tested on:
commit: 5472d60c Merge tag 'trace-v6.18-2' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=159b91e2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2b842a78bbee09b1
dashboard link: https://syzkaller.appspot.com/bug?extid=1f1fbecb9413cdbfbef8
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=11f50dcd980000
Note: testing is done by a robot and is best-effort only.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Forwarded: [PATCH] bpf: avoid sleeping in invalid context during sock_map_delete_elem path
2025-08-27 23:56 [syzbot] [bpf?] [net?] BUG: sleeping function called from invalid context in sock_map_delete_elem syzbot
` (2 preceding siblings ...)
2025-10-09 22:28 ` [PATCH] bpf: avoid sleeping in invalid context during sock_map_delete_elem path Brahmajit Das
@ 2025-10-13 16:29 ` syzbot
2025-10-13 17:11 ` [PATCH v2] " Brahmajit Das
4 siblings, 0 replies; 8+ messages in thread
From: syzbot @ 2025-10-13 16:29 UTC (permalink / raw)
To: linux-kernel
For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org.
***
Subject: [PATCH] bpf: avoid sleeping in invalid context during sock_map_delete_elem path
Author: listout@listout.xyz
#syz test
The syzkaller report exposed a BUG: “sleeping function called from
invalid context” in sock_map_delete_elem, which happens when
`bpf_test_timer_enter()` disables preemption but the delete path later
invokes a sleeping function while still in that context. Specifically:
- The crash trace shows `bpf_test_timer_enter()` acquiring a
preempt_disable path (via t->mode == NO_PREEMPT), but the symmetric
release path always calls migrate_enable(), mismatching the earlier
disable.
- As a result, preemption remains disabled across the
sock_map_delete_elem path, leading to a sleeping call under an invalid
context. :contentReference[oaicite:0]{index=0}
To fix this, normalize the disable/enable pairing: always use
migrate_disable()/migrate_enable() regardless of t->mode. This ensures
that we never remain with preemption disabled unintentionally when
entering the delete path, and avoids invalid-context sleeping.
Reported-by: syzbot+1f1fbecb9413cdbfbef8@syzkaller.appspotmail.com
Signed-off-by: Brahmajit Das <listout@listout.xyz>
---
net/bpf/test_run.c | 22 +++++++++-------------
1 file changed, 9 insertions(+), 13 deletions(-)
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index dfb03ee0bb62..92ff05821003 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2017 Facebook
*/
+#include "linux/rcupdate.h"
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/btf_ids.h>
@@ -29,7 +30,6 @@
#include <trace/events/bpf_test_run.h>
struct bpf_test_timer {
- enum { NO_PREEMPT, NO_MIGRATE } mode;
u32 i;
u64 time_start, time_spent;
};
@@ -38,10 +38,8 @@ static void bpf_test_timer_enter(struct bpf_test_timer *t)
__acquires(rcu)
{
rcu_read_lock();
- if (t->mode == NO_PREEMPT)
- preempt_disable();
- else
- migrate_disable();
+ /*migrate_disable();*/
+ rcu_read_lock_dont_migrate();
t->time_start = ktime_get_ns();
}
@@ -51,10 +49,8 @@ static void bpf_test_timer_leave(struct bpf_test_timer *t)
{
t->time_start = 0;
- if (t->mode == NO_PREEMPT)
- preempt_enable();
- else
- migrate_enable();
+ /*migrate_enable();*/
+ rcu_read_unlock_migrate();
rcu_read_unlock();
}
@@ -374,7 +370,7 @@ static int bpf_test_run_xdp_live(struct bpf_prog *prog, struct xdp_buff *ctx,
{
struct xdp_test_data xdp = { .batch_size = batch_size };
- struct bpf_test_timer t = { .mode = NO_MIGRATE };
+ struct bpf_test_timer t = {};
int ret;
if (!repeat)
@@ -404,7 +400,7 @@ static int bpf_test_run(struct bpf_prog *prog, void *ctx, u32 repeat,
struct bpf_prog_array_item item = {.prog = prog};
struct bpf_run_ctx *old_ctx;
struct bpf_cg_run_ctx run_ctx;
- struct bpf_test_timer t = { NO_MIGRATE };
+ struct bpf_test_timer t = {};
enum bpf_cgroup_storage_type stype;
int ret;
@@ -1377,7 +1373,7 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
- struct bpf_test_timer t = { NO_PREEMPT };
+ struct bpf_test_timer t = {};
u32 size = kattr->test.data_size_in;
struct bpf_flow_dissector ctx = {};
u32 repeat = kattr->test.repeat;
@@ -1445,7 +1441,7 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
int bpf_prog_test_run_sk_lookup(struct bpf_prog *prog, const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
- struct bpf_test_timer t = { NO_PREEMPT };
+ struct bpf_test_timer t = {};
struct bpf_prog_array *progs = NULL;
struct bpf_sk_lookup_kern ctx = {};
u32 repeat = kattr->test.repeat;
--
2.51.0
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH v2] bpf: avoid sleeping in invalid context during sock_map_delete_elem path
2025-08-27 23:56 [syzbot] [bpf?] [net?] BUG: sleeping function called from invalid context in sock_map_delete_elem syzbot
` (3 preceding siblings ...)
2025-10-13 16:29 ` Forwarded: [PATCH] bpf: avoid sleeping in invalid context during sock_map_delete_elem path syzbot
@ 2025-10-13 17:11 ` Brahmajit Das
4 siblings, 0 replies; 8+ messages in thread
From: Brahmajit Das @ 2025-10-13 17:11 UTC (permalink / raw)
To: syzbot+1f1fbecb9413cdbfbef8
Cc: listout, andrii, ast, bpf, daniel, davem, eddyz87, edumazet,
haoluo, horms, john.fastabend, jolsa, kpsingh, kuba, linux-kernel,
martin.lau, netdev, pabeni, sdf, song, syzkaller-bugs,
yonghong.song, Menglong Dong, Sahil Chandna
The syzkaller report exposed a BUG: “sleeping function called from
invalid context” in sock_map_delete_elem, which happens when
`bpf_test_timer_enter()` disables preemption but the delete path later
invokes a sleeping function while still in that context. Specifically:
- The crash trace shows `bpf_test_timer_enter()` acquiring a
preempt_disable path (via t->mode == NO_PREEMPT), but the symmetric
release path always calls migrate_enable(), mismatching the earlier
disable.
- As a result, preemption remains disabled across the
sock_map_delete_elem path, leading to a sleeping call under an invalid
context. :contentReference[oaicite:0]{index=0}
To fix this, normalize the disable/enable pairing: always use
migrate_disable()/migrate_enable() regardless of t->mode. This ensures
that we never remain with preemption disabled unintentionally when
entering the delete path, and avoids invalid-context sleeping.
Reported-by: syzbot+1f1fbecb9413cdbfbef8@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=1f1fbecb9413cdbfbef8
Suggested-by: Yonghong Song <yonghong.song@linux.dev>
Suggested-by: Menglong Dong <menglong.dong@linux.dev>
Co-authored-by: Sahil Chandna <chandna.linuxkernel@gmail.com>
Signed-off-by: Brahmajit Das <listout@listout.xyz>
---
Changes in v2:
- remove enum { NO_PREEMPT, NO_MIGRATE } mode
- Using rcu_read_lock_dont_migrate/rcu_read_unlock_migrate
Changes in v1:
- Changes on top of Sahil's initial work based on feedback from
Yonghong's. i.e. remove NO_PREEMPT/NO_MIGRATE in test_run.c and use
migrate_disable()/migrate_enable() universally.
Link: https://lore.kernel.org/all/d0fdced7-a9a5-473e-991f-4f5e4c13f616@linux.dev/
Please also find Sahil's v2 patch:
Link: https://lore.kernel.org/all/20251010075923.408195-1-chandna.linuxkernel@gmail.com/T/
---
net/bpf/test_run.c | 21 ++++++---------------
1 file changed, 6 insertions(+), 15 deletions(-)
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index dfb03ee0bb62..83f97ee34419 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -29,7 +29,6 @@
#include <trace/events/bpf_test_run.h>
struct bpf_test_timer {
- enum { NO_PREEMPT, NO_MIGRATE } mode;
u32 i;
u64 time_start, time_spent;
};
@@ -37,11 +36,7 @@ struct bpf_test_timer {
static void bpf_test_timer_enter(struct bpf_test_timer *t)
__acquires(rcu)
{
- rcu_read_lock();
- if (t->mode == NO_PREEMPT)
- preempt_disable();
- else
- migrate_disable();
+ rcu_read_lock_dont_migrate();
t->time_start = ktime_get_ns();
}
@@ -51,11 +46,7 @@ static void bpf_test_timer_leave(struct bpf_test_timer *t)
{
t->time_start = 0;
- if (t->mode == NO_PREEMPT)
- preempt_enable();
- else
- migrate_enable();
- rcu_read_unlock();
+ rcu_read_unlock_migrate();
}
static bool bpf_test_timer_continue(struct bpf_test_timer *t, int iterations,
@@ -374,7 +365,7 @@ static int bpf_test_run_xdp_live(struct bpf_prog *prog, struct xdp_buff *ctx,
{
struct xdp_test_data xdp = { .batch_size = batch_size };
- struct bpf_test_timer t = { .mode = NO_MIGRATE };
+ struct bpf_test_timer t = {};
int ret;
if (!repeat)
@@ -404,7 +395,7 @@ static int bpf_test_run(struct bpf_prog *prog, void *ctx, u32 repeat,
struct bpf_prog_array_item item = {.prog = prog};
struct bpf_run_ctx *old_ctx;
struct bpf_cg_run_ctx run_ctx;
- struct bpf_test_timer t = { NO_MIGRATE };
+ struct bpf_test_timer t = {};
enum bpf_cgroup_storage_type stype;
int ret;
@@ -1377,7 +1368,7 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
- struct bpf_test_timer t = { NO_PREEMPT };
+ struct bpf_test_timer t = {};
u32 size = kattr->test.data_size_in;
struct bpf_flow_dissector ctx = {};
u32 repeat = kattr->test.repeat;
@@ -1445,7 +1436,7 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
int bpf_prog_test_run_sk_lookup(struct bpf_prog *prog, const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
- struct bpf_test_timer t = { NO_PREEMPT };
+ struct bpf_test_timer t = {};
struct bpf_prog_array *progs = NULL;
struct bpf_sk_lookup_kern ctx = {};
u32 repeat = kattr->test.repeat;
--
2.51.0
^ permalink raw reply related [flat|nested] 8+ messages in thread