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Re: [PATCH v2 2/2] hw/elf_ops: clear uninitialized segment space
From: |
Laurent Vivier |
Subject: |
Re: [PATCH v2 2/2] hw/elf_ops: clear uninitialized segment space |
Date: |
Sat, 17 Apr 2021 17:36:54 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 |
Le 15/04/2021 à 12:04, Philippe Mathieu-Daudé a écrit :
> From: Laurent Vivier <laurent@vivier.eu>
>
> When the mem_size of the segment is bigger than the file_size,
> and if this space doesn't overlap another segment, it needs
> to be cleared.
>
> This bug is very similar to the one we had for linux-user,
> 22d113b52f41 ("linux-user: Fix loading of BSS segments"),
> where .bss section is encoded as an extension of the the data
> one by setting the segment p_memsz > p_filesz.
>
> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
> Message-Id: <20210414105838.205019-1-laurent@vivier.eu>
> [PMD: Use recently added address_space_set()]
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> include/hw/elf_ops.h | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/include/hw/elf_ops.h b/include/hw/elf_ops.h
> index 6ee458e7bc3..29f4c43e231 100644
> --- a/include/hw/elf_ops.h
> +++ b/include/hw/elf_ops.h
> @@ -562,6 +562,19 @@ static int glue(load_elf, SZ)(const char *name, int fd,
> if (res != MEMTX_OK) {
> goto fail;
> }
> + /*
> + * We need to zero'ify the space that is not copied
> + * from file
> + */
> + if (file_size < mem_size) {
> + res = address_space_set(as ? as :
> &address_space_memory,
> + addr + file_size, 0,
> + mem_size - file_size,
> + MEMTXATTRS_UNSPECIFIED);
> + if (res != MEMTX_OK) {
> + goto fail;
> + }
> + }
> }
> }
>
>
It seems we need also the same kind of operation with the other branch of the if
(rom_add_elf_program()), but I'm not sure where to do it:
diff --git a/hw/core/loader.c b/hw/core/loader.c
index d3e5f3b423f6..8146fdcbb7a0 100644
--- a/hw/core/loader.c
+++ b/hw/core/loader.c
@@ -1146,9 +1146,13 @@ static void rom_reset(void *unused)
if (rom->mr) {
void *host = memory_region_get_ram_ptr(rom->mr);
memcpy(host, rom->data, rom->datasize);
+ memset(host + rom->datasize, 0, rom->romsize - rom->datasize);
} else {
address_space_write_rom(rom->as, rom->addr, MEMTXATTRS_UNSPECIFIED,
rom->data, rom->datasize);
+ address_space_set(rom->as, rom->addr + rom->datasize, 0,
+ rom->romsize - rom->datasize,
+ MEMTXATTRS_UNSPECIFIED);
}
if (rom->isrom) {
/* rom needs to be written only once */
Thanks,
Laurent