* [PATCH for-9.1] linux-user: Handle short reads in mmap_h_gt_g
@ 2024-08-15 21:32 Richard Henderson
2024-08-16 1:32 ` gaosong
2024-08-16 5:57 ` Philippe Mathieu-Daudé
0 siblings, 2 replies; 4+ messages in thread
From: Richard Henderson @ 2024-08-15 21:32 UTC (permalink / raw)
To: qemu-devel; +Cc: gaosong, qemu-stable
In particular, if an image has a large bss, we can hit
EOF before reading all host_len bytes of the mapping.
Cc: qemu-stable@nongnu.org
Fixes: eb5027ac618 ("linux-user: Split out mmap_h_gt_g")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2504
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
linux-user/mmap.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index 6418e811f6..de9ab13754 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -853,10 +853,21 @@ static abi_long mmap_h_gt_g(abi_ulong start, abi_ulong len,
}
if (misaligned_offset) {
- /* TODO: The read could be short. */
- if (pread(fd, p, host_len, offset + real_start - start) != host_len) {
- do_munmap(p, host_len);
- return -1;
+ size_t o = 0;
+ while (1) {
+ ssize_t r = pread(fd, p + o, host_len - o,
+ o + offset + real_start - start);
+ if (likely(r == host_len - o) || r == 0) {
+ /* Complete or EOF */
+ break;
+ }
+ if (unlikely(r == -1)) {
+ /* Error */
+ do_munmap(p, host_len);
+ return -1;
+ }
+ /* Short read -- iterate */
+ o += r;
}
if (!(host_prot & PROT_WRITE)) {
mprotect(p, host_len, host_prot);
--
2.43.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH for-9.1] linux-user: Handle short reads in mmap_h_gt_g
2024-08-15 21:32 [PATCH for-9.1] linux-user: Handle short reads in mmap_h_gt_g Richard Henderson
@ 2024-08-16 1:32 ` gaosong
2024-08-16 5:57 ` Philippe Mathieu-Daudé
1 sibling, 0 replies; 4+ messages in thread
From: gaosong @ 2024-08-16 1:32 UTC (permalink / raw)
To: Richard Henderson, qemu-devel; +Cc: qemu-stable
在 2024/8/16 上午5:32, Richard Henderson 写道:
> In particular, if an image has a large bss, we can hit
> EOF before reading all host_len bytes of the mapping.
>
> Cc: qemu-stable@nongnu.org
> Fixes: eb5027ac618 ("linux-user: Split out mmap_h_gt_g")
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2504
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> linux-user/mmap.c | 19 +++++++++++++++----
> 1 file changed, 15 insertions(+), 4 deletions(-)
Reviewed-by: Song Gao <gaosong@loongson.cn>
Tested-by: Song Gao <gaosong@loongson.cn>
Thanks.
Song Gao
> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
> index 6418e811f6..de9ab13754 100644
> --- a/linux-user/mmap.c
> +++ b/linux-user/mmap.c
> @@ -853,10 +853,21 @@ static abi_long mmap_h_gt_g(abi_ulong start, abi_ulong len,
> }
>
> if (misaligned_offset) {
> - /* TODO: The read could be short. */
> - if (pread(fd, p, host_len, offset + real_start - start) != host_len) {
> - do_munmap(p, host_len);
> - return -1;
> + size_t o = 0;
> + while (1) {
> + ssize_t r = pread(fd, p + o, host_len - o,
> + o + offset + real_start - start);
> + if (likely(r == host_len - o) || r == 0) {
> + /* Complete or EOF */
> + break;
> + }
> + if (unlikely(r == -1)) {
> + /* Error */
> + do_munmap(p, host_len);
> + return -1;
> + }
> + /* Short read -- iterate */
> + o += r;
> }
> if (!(host_prot & PROT_WRITE)) {
> mprotect(p, host_len, host_prot);
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH for-9.1] linux-user: Handle short reads in mmap_h_gt_g
2024-08-15 21:32 [PATCH for-9.1] linux-user: Handle short reads in mmap_h_gt_g Richard Henderson
2024-08-16 1:32 ` gaosong
@ 2024-08-16 5:57 ` Philippe Mathieu-Daudé
2024-08-16 8:10 ` Richard Henderson
1 sibling, 1 reply; 4+ messages in thread
From: Philippe Mathieu-Daudé @ 2024-08-16 5:57 UTC (permalink / raw)
To: Richard Henderson, qemu-devel; +Cc: gaosong, qemu-stable, Warner Losh
On 15/8/24 23:32, Richard Henderson wrote:
> In particular, if an image has a large bss, we can hit
> EOF before reading all host_len bytes of the mapping.
>
> Cc: qemu-stable@nongnu.org
> Fixes: eb5027ac618 ("linux-user: Split out mmap_h_gt_g")
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2504
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> linux-user/mmap.c | 19 +++++++++++++++----
> 1 file changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
> index 6418e811f6..de9ab13754 100644
> --- a/linux-user/mmap.c
> +++ b/linux-user/mmap.c
> @@ -853,10 +853,21 @@ static abi_long mmap_h_gt_g(abi_ulong start, abi_ulong len,
> }
>
> if (misaligned_offset) {
> - /* TODO: The read could be short. */
I note there are other short reads in {linux,bsd}-user/mmap.c.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> - if (pread(fd, p, host_len, offset + real_start - start) != host_len) {
> - do_munmap(p, host_len);
> - return -1;
> + size_t o = 0;
> + while (1) {
> + ssize_t r = pread(fd, p + o, host_len - o,
> + o + offset + real_start - start);
> + if (likely(r == host_len - o) || r == 0) {
> + /* Complete or EOF */
> + break;
> + }
> + if (unlikely(r == -1)) {
> + /* Error */
> + do_munmap(p, host_len);
> + return -1;
> + }
> + /* Short read -- iterate */
> + o += r;
> }
> if (!(host_prot & PROT_WRITE)) {
> mprotect(p, host_len, host_prot);
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH for-9.1] linux-user: Handle short reads in mmap_h_gt_g
2024-08-16 5:57 ` Philippe Mathieu-Daudé
@ 2024-08-16 8:10 ` Richard Henderson
0 siblings, 0 replies; 4+ messages in thread
From: Richard Henderson @ 2024-08-16 8:10 UTC (permalink / raw)
To: Philippe Mathieu-Daudé, qemu-devel; +Cc: gaosong, qemu-stable, Warner Losh
On 8/16/24 15:57, Philippe Mathieu-Daudé wrote:
> On 15/8/24 23:32, Richard Henderson wrote:
>> In particular, if an image has a large bss, we can hit
>> EOF before reading all host_len bytes of the mapping.
>>
>> Cc: qemu-stable@nongnu.org
>> Fixes: eb5027ac618 ("linux-user: Split out mmap_h_gt_g")
>> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2504
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>> linux-user/mmap.c | 19 +++++++++++++++----
>> 1 file changed, 15 insertions(+), 4 deletions(-)
>>
>> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
>> index 6418e811f6..de9ab13754 100644
>> --- a/linux-user/mmap.c
>> +++ b/linux-user/mmap.c
>> @@ -853,10 +853,21 @@ static abi_long mmap_h_gt_g(abi_ulong start, abi_ulong len,
>> }
>> if (misaligned_offset) {
>> - /* TODO: The read could be short. */
>
> I note there are other short reads in {linux,bsd}-user/mmap.c.
Ah, via mmap_frag. Hmm, yes. Worth fixing at the same time.
r~
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2024-08-16 8:10 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2024-08-15 21:32 [PATCH for-9.1] linux-user: Handle short reads in mmap_h_gt_g Richard Henderson
2024-08-16 1:32 ` gaosong
2024-08-16 5:57 ` Philippe Mathieu-Daudé
2024-08-16 8:10 ` Richard Henderson
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).