linux-kernel - Re: [resend PATCH] riscv: fix memory leakage in process_accumulated_relocations

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Message-ID: <d76f62d5-b461-4bff-baa7-62d0eabbf2cd@ghiti.fr>
Date: Fri, 7 Mar 2025 10:08:55 +0100
From: Alexandre Ghiti <alex@...ti.fr>
To: laokz <zhangkai@...as.ac.cn>, Walmsley <paul.walmsley@...ive.com>,
 Dabbelt <palmer@...belt.com>, Ou <aou@...s.berkeley.edu>,
 linux-riscv@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org
Subject: Re: [resend PATCH] riscv: fix memory leakage in
 process_accumulated_relocations

Hi Kai,

On 16/11/2024 13:07, laokz wrote:
> Sorry for last weird email.
> ---
>
> When module relocation is done, process_accumulated_relocations()
> frees all dynamic allocated memory. rel_head_iter->rel_entry is
> missed to free that kmemleak might report:
>
> unreferenced object 0xffffffd880c5fc40 (size 16):
>    comm "insmod", pid 1101, jiffies 4295045138
>    hex dump (first 16 bytes):
>      e0 c0 f5 87 d8 ff ff ff 60 c5 f5 87 d8 ff ff ff  ........`.......
>    backtrace (crc d2ecb20c):
>      [<00000000b01655f6>] kmalloc_trace_noprof+0x268/0x2f6
>      [<000000006dc0067a>]
> add_relocation_to_accumulate.constprop.0+0xf2/0x1aa
>      [<00000000e1b29a36>] apply_relocate_add+0x13c/0x36e
>      [<000000007543f1fb>] load_module+0x5c6/0x83e
>      [<00000000abce12e8>] init_module_from_file+0x74/0xaa
>      [<0000000049413e3d>] idempotent_init_module+0x116/0x22e
>      [<00000000f9b98b85>] __riscv_sys_finit_module+0x62/0xae
>
> Signed-off-by: Kai Zhang <zhangkai@...as.ac.cn>
> ---
>   arch/riscv/kernel/module.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
> index 1cd461f3d87..f8c3c4b47dc 100644
> --- a/arch/riscv/kernel/module.c
> +++ b/arch/riscv/kernel/module.c
> @@ -643,6 +643,7 @@ process_accumulated_relocations(struct module *me,
>                          }
>                          reloc_handlers[curr_type].accumulate_handler(
>                                  me, location, buffer);
> +                       kfree(rel_head_iter->rel_entry);
>                          kfree(rel_head_iter);
>                  }
>                  kfree(bucket_iter);
>
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

This patch is not relevant anymore since commit 03f0b548537f ("riscv: 
module: remove relocation_head rel_entry member allocation") which 
turned the dynamic allocation of rel_entry into a static allocation.

Thanks anyway Kai, that was a good catch.

Alex

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