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time/jiffies: Saturate in mult_hz() instead of wrapping

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Return ULONG_MAX for values that don't fit an unsigned long.
proc_int_u2k_conv_uop() now correctly rejects a result above INT_MAX.

This is the erroneous behaviour that is being fixed. The input has to
exceed ULONG_MAX / HZ for the product to wrap, so the value below is
specific to CONFIG_HZ=1000:

  # echo 18446744073709552 > /proc/sys/net/ipv4/tcp_keepalive_time
  # cat /proc/sys/net/ipv4/tcp_keepalive_time
  0

That value is now rejected with an error.

The original bound ("*u_ptr > INT_MAX / HZ") was removed in commit
2dc164a48e ("sysctl: Create converter functions with two new macros").

Fixes: 2dc164a48e ("sysctl: Create converter functions with two new macros")
Cc: stable@vger.kernel.org
Signed-off-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
This commit is contained in:
Zhan Xusheng 2026-09-28 10:02:05 +08:00 committed by Joel Granados
parent e955f14fa8
commit fdd6553e1e
1 changed files with 2 additions and 0 deletions
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2
kernel/time/jiffies.c
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@ -101,6 +101,8 @@ void __init register_refined_jiffies(long cycles_per_second)
#ifdef CONFIG_SYSCTL
static ulong mult_hz(const ulong val)
{
if (val >= ULONG_MAX / HZ)
return ULONG_MAX;
return val * HZ;
}