* [Qemu-devel] [PATCH] Fix page_check_range() wrap-around check when len=0.
@ 2010-03-28 0:53 takasi-y
0 siblings, 0 replies; only message in thread
From: takasi-y @ 2010-03-28 0:53 UTC (permalink / raw
To: qemu-devel; +Cc: Richard Henderson
Fix page_check_range() wrap-around check when len=0.
write(1,"",0) on linux-user emulation should be OK, but fails.
This is a regression brought by 376a7909.
This patch fixes it at the last of the calling path shown below,
do_syscall:write -> access_ok() -> page_check_range(),
as linux-kernel does. For example, x86 does it at follows,
sys_write() -> access_ok() -> __range_not_ok().
This implies calling page_check_range() with len=0 is valid.
Signed-off-by: Takashi YOSHII <takasi-y@ops.dti.ne.jp>
---
exec.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/exec.c b/exec.c
index 14767b7..26cd8b9 100644
--- a/exec.c
+++ b/exec.c
@@ -2410,7 +2410,7 @@ int page_check_range(target_ulong start, target_ulong len, int flags)
assert(start < ((abi_ulong)1 << L1_MAP_ADDR_SPACE_BITS));
#endif
- if (start + len - 1 < start) {
+ if (len > 0 && start + len -1 < start) {
/* We've wrapped around. */
return -1;
}
--
1.6.5
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2010-03-28 0:53 [Qemu-devel] [PATCH] Fix page_check_range() wrap-around check when len=0 takasi-y
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