[PATCH net v2 5/5] net: restrict message_cost and message_burst to non-negative values
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From: Jiayuan Chen <jiayuan.chen@linux.dev>
Date: 2026-10-27 10:49:55
Also in:
linux-doc, lkml, stable
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Revision v2 (2 revisions archived).
Revisions (2)
- v1
- v2 current [diff against previous]
net.core.message_cost and net.core.message_burst feed the interval and
burst of net_ratelimit_state, but neither rejects negative values:
message_burst uses plain proc_dointvec, and message_cost uses
proc_dointvec_jiffies, which happily stores -1 second as -HZ jiffies.
Since commit a940d145cc38 ("ratelimit: Warn if ->interval or ->burst are
negative"), ___ratelimit() splats on such values, so the next
net_ratelimit() caller warns, e.g. a martian source log:
Negative interval (-250) or burst (10): Uninitialized ratelimit_state structure?
WARNING: lib/ratelimit.c:43 at ___ratelimit+0x56e/0x960, CPU#1: ping/3218
RIP: 0010:___ratelimit+0x578/0x960
Call Trace:
<IRQ>
net_ratelimit+0x1c/0x30
ip_handle_martian_source+0x1bb/0x340
ip_route_input_slow+0x1057/0x3650
ip_route_input_noref+0x104/0x260
arp_process+0x109b/0x2510
arp_rcv+0x381/0x460
__netif_receive_skb_one_core+0x173/0x1c0
__netif_receive_skb+0x21/0x150
process_backlog+0x37e/0x1200
__napi_poll.constprop.0+0xa5/0x5e0
net_rx_action+0x4c0/0xf70
handle_softirqs+0x204/0x9b0
__do_softirq+0x10/0x18
do_softirq.part.0+0x49/0xd0
</IRQ>
Negative values never meant anything here: 0 already expresses both
"no limit" (interval) and "suppress everything" (burst).
Reject them at write time. message_burst can simply use
proc_dointvec_minmax with extra1 = 0. proc_dointvec_jiffies has no
minmax variant, so add proc_dointvec_jiffies_minmax(), mirroring
proc_dointvec_ms_jiffies_minmax(), and use it for message_cost with
extra1 = 0. Note that like the ms variant, extra1/extra2 are compared
against the converted jiffies value.
Fixes: a940d145cc38 ("ratelimit: Warn if ->interval or ->burst are negative")
Cc: <redacted>
Suggested-by: Joel Granados <joel.granados@kernel.org>
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
---
include/linux/jiffies.h | 2 ++
kernel/time/jiffies.c | 40 ++++++++++++++++++++++++++++++++++++++
net/core/sysctl_net_core.c | 6 ++++--
3 files changed, 46 insertions(+), 2 deletions(-)
diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h
index bbd57061802cd..de12920f8e94b 100644
--- a/include/linux/jiffies.h
+++ b/include/linux/jiffies.h@@ -646,6 +646,8 @@ extern unsigned long nsecs_to_jiffies(u64 n); struct ctl_table; int proc_dointvec_jiffies(const struct ctl_table *table, int dir, void *buffer, size_t *lenp, loff_t *ppos); +int proc_dointvec_jiffies_minmax(const struct ctl_table *table, int dir, + void *buffer, size_t *lenp, loff_t *ppos); int proc_dointvec_ms_jiffies_minmax(const struct ctl_table *table, int dir, void *buffer, size_t *lenp, loff_t *ppos); int proc_dointvec_userhz_jiffies(const struct ctl_table *table, int dir,
diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c
index 9b3487d40cd6a..22a70caa58bc1 100644
--- a/kernel/time/jiffies.c
+++ b/kernel/time/jiffies.c@@ -165,6 +165,14 @@ static int do_proc_int_conv_jiffies(bool *negp, ulong *u_ptr, int *k_ptr, sysctl_u2k_int_conv_hz, sysctl_k2u_int_conv_hz); } +static int do_proc_int_conv_jiffies_minmax(bool *negp, ulong *u_ptr, + int *k_ptr, int dir, + const struct ctl_table *tbl) +{ + return proc_int_conv(negp, u_ptr, k_ptr, dir, tbl, true, + sysctl_u2k_int_conv_hz, sysctl_k2u_int_conv_hz); +} + static int do_proc_int_conv_userhz_jiffies(bool *negp, ulong *u_ptr, int *k_ptr, int dir, const struct ctl_table *tbl)
@@ -213,6 +221,13 @@ static int do_proc_int_conv_jiffies(bool *negp, ulong *u_ptr, int *k_ptr, return -ENOSYS; } +static int do_proc_int_conv_jiffies_minmax(bool *negp, ulong *u_ptr, + int *k_ptr, int dir, + const struct ctl_table *tbl) +{ + return -ENOSYS; +} + static int do_proc_int_conv_userhz_jiffies(bool *negp, ulong *u_ptr, int *k_ptr, int dir, const struct ctl_table *tbl)
@@ -263,6 +278,31 @@ int proc_dointvec_jiffies(const struct ctl_table *table, int dir, } EXPORT_SYMBOL(proc_dointvec_jiffies); +/** + * proc_dointvec_jiffies_minmax - read a vector of integers as seconds with min/max values + * @table: the sysctl table + * @dir: %TRUE if this is a write to the sysctl file + * @buffer: the user buffer + * @lenp: the size of the user buffer + * @ppos: file position + * + * Reads/writes up to table->maxlen/sizeof(unsigned int) integer + * values from/to the user buffer, treated as an ASCII string. + * The values read are assumed to be in seconds, and are converted into + * jiffies. The converted values are checked against the optional + * table->extra1 (min) and table->extra2 (max) bounds, in jiffies; + * a value outside the range is rejected with -EINVAL. + * + * Returns 0 on success. + */ +int proc_dointvec_jiffies_minmax(const struct ctl_table *table, int dir, + void *buffer, size_t *lenp, loff_t *ppos) +{ + return proc_dointvec_conv(table, dir, buffer, lenp, ppos, + do_proc_int_conv_jiffies_minmax); +} +EXPORT_SYMBOL(proc_dointvec_jiffies_minmax); + /** * proc_dointvec_userhz_jiffies - read a vector of integers as 1/USER_HZ seconds * @table: the sysctl table
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 473c162736d69..9226b96f2e89b 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c@@ -544,14 +544,16 @@ static struct ctl_table net_core_table[] = { .data = &net_ratelimit_state.interval, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_dointvec_jiffies, + .proc_handler = proc_dointvec_jiffies_minmax, + .extra1 = SYSCTL_ZERO, }, { .procname = "message_burst", .data = &net_ratelimit_state.burst, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_dointvec, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, }, #ifdef CONFIG_RPS {
--
2.43.0