* [PATCH] hw/elf_ops: Ignore loadable segments with zero size
@ 2024-01-16 15:50 Bin Meng
2024-01-16 16:38 ` Richard Henderson
2024-01-17 8:18 ` Philippe Mathieu-Daudé
0 siblings, 2 replies; 5+ messages in thread
From: Bin Meng @ 2024-01-16 15:50 UTC (permalink / raw)
To: qemu-devel, Richard Henderson, Thomas Huth
Some ELF files really do have segments of zero size, e.g.:
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
RISCV_ATTRIBUT 0x00000000000025b8 0x0000000000000000 0x0000000000000000
0x000000000000003e 0x0000000000000000 R 0x1
LOAD 0x0000000000001000 0x0000000080200000 0x0000000080200000
0x00000000000001d1 0x00000000000001d1 R E 0x1000
LOAD 0x00000000000011d1 0x00000000802001d1 0x00000000802001d1
0x0000000000000e37 0x0000000000000e37 RW 0x1000
LOAD 0x0000000000000120 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 0x1000
The current logic does not check for this condition, resulting in
the incorrect assignment of 'lowaddr' as zero.
There is already a piece of codes inside the segment traversal loop
that checks for zero-sized loadable segments for not creating empty
ROM blobs. Let's move this check to the beginning of the loop to
cover both scenarios.
Signed-off-by: Bin Meng <bmeng@tinylab.org>
---
include/hw/elf_ops.h | 75 +++++++++++++++++++++++---------------------
1 file changed, 39 insertions(+), 36 deletions(-)
diff --git a/include/hw/elf_ops.h b/include/hw/elf_ops.h
index 0a5c258fe6..f014399b50 100644
--- a/include/hw/elf_ops.h
+++ b/include/hw/elf_ops.h
@@ -427,6 +427,16 @@ static ssize_t glue(load_elf, SZ)(const char *name, int fd,
file_size = ph->p_filesz; /* Size of the allocated data */
data_offset = ph->p_offset; /* Offset where the data is located */
+ /*
+ * Some ELF files really do have segments of zero size;
+ * just ignore them rather than trying to set the wrong addr,
+ * or create empty ROM blobs, because the zero-length blob can
+ * falsely trigger the overlapping-ROM-blobs check.
+ */
+ if (mem_size == 0) {
+ continue;
+ }
+
if (file_size > 0) {
if (g_mapped_file_get_length(mapped_file) <
file_size + data_offset) {
@@ -530,45 +540,38 @@ static ssize_t glue(load_elf, SZ)(const char *name, int fd,
*pentry = ehdr.e_entry - ph->p_vaddr + ph->p_paddr;
}
- /* Some ELF files really do have segments of zero size;
- * just ignore them rather than trying to create empty
- * ROM blobs, because the zero-length blob can falsely
- * trigger the overlapping-ROM-blobs check.
- */
- if (mem_size != 0) {
- if (load_rom) {
- g_autofree char *label =
- g_strdup_printf("%s ELF program header segment %d",
- name, i);
-
- /*
- * rom_add_elf_program() takes its own reference to
- * 'mapped_file'.
- */
- rom_add_elf_program(label, mapped_file, data, file_size,
- mem_size, addr, as);
- } else {
- MemTxResult res;
-
- res = address_space_write(as ? as : &address_space_memory,
- addr, MEMTXATTRS_UNSPECIFIED,
- data, file_size);
+ if (load_rom) {
+ g_autofree char *label =
+ g_strdup_printf("%s ELF program header segment %d",
+ name, i);
+
+ /*
+ * rom_add_elf_program() takes its own reference to
+ * 'mapped_file'.
+ */
+ rom_add_elf_program(label, mapped_file, data, file_size,
+ mem_size, addr, as);
+ } else {
+ MemTxResult res;
+
+ res = address_space_write(as ? as : &address_space_memory,
+ addr, MEMTXATTRS_UNSPECIFIED,
+ data, file_size);
+ 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;
}
- /*
- * 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;
- }
- }
}
}
--
2.34.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] hw/elf_ops: Ignore loadable segments with zero size
2024-01-16 15:50 [PATCH] hw/elf_ops: Ignore loadable segments with zero size Bin Meng
@ 2024-01-16 16:38 ` Richard Henderson
2024-01-20 10:28 ` Michael Tokarev
2024-01-17 8:18 ` Philippe Mathieu-Daudé
1 sibling, 1 reply; 5+ messages in thread
From: Richard Henderson @ 2024-01-16 16:38 UTC (permalink / raw)
To: Bin Meng, qemu-devel, Thomas Huth
On 1/17/24 02:50, Bin Meng wrote:
> Some ELF files really do have segments of zero size, e.g.:
>
> Program Headers:
> Type Offset VirtAddr PhysAddr
> FileSiz MemSiz Flags Align
> RISCV_ATTRIBUT 0x00000000000025b8 0x0000000000000000 0x0000000000000000
> 0x000000000000003e 0x0000000000000000 R 0x1
> LOAD 0x0000000000001000 0x0000000080200000 0x0000000080200000
> 0x00000000000001d1 0x00000000000001d1 R E 0x1000
> LOAD 0x00000000000011d1 0x00000000802001d1 0x00000000802001d1
> 0x0000000000000e37 0x0000000000000e37 RW 0x1000
> LOAD 0x0000000000000120 0x0000000000000000 0x0000000000000000
> 0x0000000000000000 0x0000000000000000 0x1000
>
> The current logic does not check for this condition, resulting in
> the incorrect assignment of 'lowaddr' as zero.
>
> There is already a piece of codes inside the segment traversal loop
> that checks for zero-sized loadable segments for not creating empty
> ROM blobs. Let's move this check to the beginning of the loop to
> cover both scenarios.
>
> Signed-off-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
But please report this as a bug to whatever tool produced such nonsense.
r~
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] hw/elf_ops: Ignore loadable segments with zero size
2024-01-16 15:50 [PATCH] hw/elf_ops: Ignore loadable segments with zero size Bin Meng
2024-01-16 16:38 ` Richard Henderson
@ 2024-01-17 8:18 ` Philippe Mathieu-Daudé
1 sibling, 0 replies; 5+ messages in thread
From: Philippe Mathieu-Daudé @ 2024-01-17 8:18 UTC (permalink / raw)
To: Bin Meng, qemu-devel, Richard Henderson, Thomas Huth
On 16/1/24 16:50, Bin Meng wrote:
> Some ELF files really do have segments of zero size, e.g.:
>
> Program Headers:
> Type Offset VirtAddr PhysAddr
> FileSiz MemSiz Flags Align
> RISCV_ATTRIBUT 0x00000000000025b8 0x0000000000000000 0x0000000000000000
> 0x000000000000003e 0x0000000000000000 R 0x1
> LOAD 0x0000000000001000 0x0000000080200000 0x0000000080200000
> 0x00000000000001d1 0x00000000000001d1 R E 0x1000
> LOAD 0x00000000000011d1 0x00000000802001d1 0x00000000802001d1
> 0x0000000000000e37 0x0000000000000e37 RW 0x1000
> LOAD 0x0000000000000120 0x0000000000000000 0x0000000000000000
> 0x0000000000000000 0x0000000000000000 0x1000
>
> The current logic does not check for this condition, resulting in
> the incorrect assignment of 'lowaddr' as zero.
>
> There is already a piece of codes inside the segment traversal loop
> that checks for zero-sized loadable segments for not creating empty
> ROM blobs. Let's move this check to the beginning of the loop to
> cover both scenarios.
>
> Signed-off-by: Bin Meng <bmeng@tinylab.org>
> ---
>
> include/hw/elf_ops.h | 75 +++++++++++++++++++++++---------------------
> 1 file changed, 39 insertions(+), 36 deletions(-)
Thanks, patch queued.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] hw/elf_ops: Ignore loadable segments with zero size
2024-01-16 16:38 ` Richard Henderson
@ 2024-01-20 10:28 ` Michael Tokarev
2024-01-20 21:25 ` Richard Henderson
0 siblings, 1 reply; 5+ messages in thread
From: Michael Tokarev @ 2024-01-20 10:28 UTC (permalink / raw)
To: Richard Henderson, Bin Meng, qemu-devel, Thomas Huth
16.01.2024 19:38, Richard Henderson wrote:
> On 1/17/24 02:50, Bin Meng wrote:
>> Some ELF files really do have segments of zero size, e.g.:
>>
>> Program Headers:
>> Type Offset VirtAddr PhysAddr
>> FileSiz MemSiz Flags Align
>> RISCV_ATTRIBUT 0x00000000000025b8 0x0000000000000000 0x0000000000000000
>> 0x000000000000003e 0x0000000000000000 R 0x1
>> LOAD 0x0000000000001000 0x0000000080200000 0x0000000080200000
>> 0x00000000000001d1 0x00000000000001d1 R E 0x1000
>> LOAD 0x00000000000011d1 0x00000000802001d1 0x00000000802001d1
>> 0x0000000000000e37 0x0000000000000e37 RW 0x1000
>> LOAD 0x0000000000000120 0x0000000000000000 0x0000000000000000
>> 0x0000000000000000 0x0000000000000000 0x1000
>>
>> The current logic does not check for this condition, resulting in
>> the incorrect assignment of 'lowaddr' as zero.
>>
>> There is already a piece of codes inside the segment traversal loop
>> that checks for zero-sized loadable segments for not creating empty
>> ROM blobs. Let's move this check to the beginning of the loop to
>> cover both scenarios.
>>
>> Signed-off-by: Bin Meng <bmeng@tinylab.org>
>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
>
> But please report this as a bug to whatever tool produced such nonsense.
I think we've an old bug about this in debian bts, https://bugs.debian.org/919921 .
/mjt
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] hw/elf_ops: Ignore loadable segments with zero size
2024-01-20 10:28 ` Michael Tokarev
@ 2024-01-20 21:25 ` Richard Henderson
0 siblings, 0 replies; 5+ messages in thread
From: Richard Henderson @ 2024-01-20 21:25 UTC (permalink / raw)
To: Michael Tokarev, Bin Meng, qemu-devel, Thomas Huth
On 1/20/24 21:28, Michael Tokarev wrote:
> 16.01.2024 19:38, Richard Henderson wrote:
>> On 1/17/24 02:50, Bin Meng wrote:
>>> Some ELF files really do have segments of zero size, e.g.:
>>>
>>> Program Headers:
>>> Type Offset VirtAddr PhysAddr
>>> FileSiz MemSiz Flags Align
>>> RISCV_ATTRIBUT 0x00000000000025b8 0x0000000000000000 0x0000000000000000
>>> 0x000000000000003e 0x0000000000000000 R 0x1
>>> LOAD 0x0000000000001000 0x0000000080200000 0x0000000080200000
>>> 0x00000000000001d1 0x00000000000001d1 R E 0x1000
>>> LOAD 0x00000000000011d1 0x00000000802001d1 0x00000000802001d1
>>> 0x0000000000000e37 0x0000000000000e37 RW 0x1000
>>> LOAD 0x0000000000000120 0x0000000000000000 0x0000000000000000
>>> 0x0000000000000000 0x0000000000000000 0x1000
>>>
>>> The current logic does not check for this condition, resulting in
>>> the incorrect assignment of 'lowaddr' as zero.
>>>
>>> There is already a piece of codes inside the segment traversal loop
>>> that checks for zero-sized loadable segments for not creating empty
>>> ROM blobs. Let's move this check to the beginning of the loop to
>>> cover both scenarios.
>>>
>>> Signed-off-by: Bin Meng <bmeng@tinylab.org>
>>
>> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
>>
>> But please report this as a bug to whatever tool produced such nonsense.
>
> I think we've an old bug about this in debian bts, https://bugs.debian.org/919921 .
That's different -- file size == 0, mem size != 0.
r~
^ permalink raw reply [flat|nested] 5+ messages in thread
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2024-01-16 15:50 [PATCH] hw/elf_ops: Ignore loadable segments with zero size Bin Meng
2024-01-16 16:38 ` Richard Henderson
2024-01-20 10:28 ` Michael Tokarev
2024-01-20 21:25 ` Richard Henderson
2024-01-17 8:18 ` Philippe Mathieu-Daudé
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