* [PATCH] linux-user: Use "!= 0" when checking if MAP_FIXED_NOREPLACE is non-zero
@ 2020-11-03 14:26 Peter Maydell
2020-11-03 14:42 ` Philippe Mathieu-Daudé
2020-11-04 21:26 ` Laurent Vivier
0 siblings, 2 replies; 3+ messages in thread
From: Peter Maydell @ 2020-11-03 14:26 UTC (permalink / raw)
To: qemu-devel; +Cc: Laurent Vivier
In pgd_find_hole_fallback(), Coverity doesn't like the use
of "if (MAP_FIXED_NOREPLACE || ...)" because it's using a
logical operator on a constant other than 0 or 1 and its
heuristic thinks we might have intended a bitwise operator
instead.
The logic is correct (we are checking whether the host really
has a MAP_FIXED_NOREPLACE or whether we fell back to the
"#define as 0 to ignore" from osdep.h); make Coverity
happier by explicitly writing out the comparison with zero.
Fixes: Coverity CID 1431059
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
linux-user/elfload.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index e19d0b5cb05..0b02a926025 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -2188,7 +2188,8 @@ static uintptr_t pgd_find_hole_fallback(uintptr_t guest_size, uintptr_t brk,
PROT_NONE, flags, -1, 0);
if (mmap_start != MAP_FAILED) {
munmap((void *) align_start, guest_size);
- if (MAP_FIXED_NOREPLACE || mmap_start == (void *) align_start) {
+ if (MAP_FIXED_NOREPLACE != 0 ||
+ mmap_start == (void *) align_start) {
return (uintptr_t) mmap_start + offset;
}
}
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] linux-user: Use "!= 0" when checking if MAP_FIXED_NOREPLACE is non-zero
2020-11-03 14:26 [PATCH] linux-user: Use "!= 0" when checking if MAP_FIXED_NOREPLACE is non-zero Peter Maydell
@ 2020-11-03 14:42 ` Philippe Mathieu-Daudé
2020-11-04 21:26 ` Laurent Vivier
1 sibling, 0 replies; 3+ messages in thread
From: Philippe Mathieu-Daudé @ 2020-11-03 14:42 UTC (permalink / raw)
To: Peter Maydell, qemu-devel; +Cc: Laurent Vivier
On 11/3/20 3:26 PM, Peter Maydell wrote:
> In pgd_find_hole_fallback(), Coverity doesn't like the use
> of "if (MAP_FIXED_NOREPLACE || ...)" because it's using a
> logical operator on a constant other than 0 or 1 and its
> heuristic thinks we might have intended a bitwise operator
> instead.
>
> The logic is correct (we are checking whether the host really
> has a MAP_FIXED_NOREPLACE or whether we fell back to the
> "#define as 0 to ignore" from osdep.h); make Coverity
> happier by explicitly writing out the comparison with zero.
>
> Fixes: Coverity CID 1431059
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> linux-user/elfload.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] linux-user: Use "!= 0" when checking if MAP_FIXED_NOREPLACE is non-zero
2020-11-03 14:26 [PATCH] linux-user: Use "!= 0" when checking if MAP_FIXED_NOREPLACE is non-zero Peter Maydell
2020-11-03 14:42 ` Philippe Mathieu-Daudé
@ 2020-11-04 21:26 ` Laurent Vivier
1 sibling, 0 replies; 3+ messages in thread
From: Laurent Vivier @ 2020-11-04 21:26 UTC (permalink / raw)
To: Peter Maydell, qemu-devel
Le 03/11/2020 à 15:26, Peter Maydell a écrit :
> In pgd_find_hole_fallback(), Coverity doesn't like the use
> of "if (MAP_FIXED_NOREPLACE || ...)" because it's using a
> logical operator on a constant other than 0 or 1 and its
> heuristic thinks we might have intended a bitwise operator
> instead.
>
> The logic is correct (we are checking whether the host really
> has a MAP_FIXED_NOREPLACE or whether we fell back to the
> "#define as 0 to ignore" from osdep.h); make Coverity
> happier by explicitly writing out the comparison with zero.
>
> Fixes: Coverity CID 1431059
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> linux-user/elfload.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> index e19d0b5cb05..0b02a926025 100644
> --- a/linux-user/elfload.c
> +++ b/linux-user/elfload.c
> @@ -2188,7 +2188,8 @@ static uintptr_t pgd_find_hole_fallback(uintptr_t guest_size, uintptr_t brk,
> PROT_NONE, flags, -1, 0);
> if (mmap_start != MAP_FAILED) {
> munmap((void *) align_start, guest_size);
> - if (MAP_FIXED_NOREPLACE || mmap_start == (void *) align_start) {
> + if (MAP_FIXED_NOREPLACE != 0 ||
> + mmap_start == (void *) align_start) {
> return (uintptr_t) mmap_start + offset;
> }
> }
>
Applied to my linux-user-for-5.2 branch.
Thanks,
Laurent
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-11-04 21:26 ` Laurent Vivier
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