In older versions of glibc (through 2.3), the dynamic linker executes a
small amount of code from the data segment, which is not marked as
executable. A recent change (commit 9ba4ace39fdfe22268daca9f28c5df384ae462cf)
stops this from working; there should be a deprecation period before
older glibc versions stop working.
The problem has been observed on glibc 2.2. While glibc 2.3 has the same
code, I did not see the problem; it may be that it accesses the page in
question as data before executing from it, and thus it is already mapped.
Signed-off-by: Scott Wood <[EMAIL PROTECTED]>
---
Unfortunately, this didn't make it into 2.6.22, but it should probably go
into the stable branch...
arch/powerpc/mm/fault.c | 22 +++++++++++++++++++++-
1 files changed, 21 insertions(+), 1 deletions(-)
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 0ece513..2445512 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -125,6 +125,18 @@ static void do_dabr(struct pt_regs *regs, unsigned long
address,
}
#endif /* !(CONFIG_4xx || CONFIG_BOOKE)*/
+#ifdef CONFIG_PPC32
+static void warn_exec_from_noexec(void)
+{
+ if (printk_ratelimit())
+ printk(KERN_WARNING "Process %s (%d) attempted to execute from "
+ "a non-executable page.\n"
+ KERN_WARNING "This may stop working in future kernels. "
+ "Please upgrade your libc.\n",
+ current->comm, current->pid);
+}
+#endif
+
/*
* For 600- and 800-family processors, the error_code parameter is DSISR
* for a data fault, SRR1 for an instruction fault. For 400-family processors
@@ -283,8 +295,16 @@ good_area:
/* protection fault */
if (error_code & DSISR_PROTFAULT)
goto bad_area;
- if (!(vma->vm_flags & VM_EXEC))
+ if (!(vma->vm_flags & VM_EXEC)) {
+#ifdef CONFIG_PPC32
+ if (vma->vm_flags & VM_READ)
+ warn_exec_from_noexec();
+ else
+ goto bad_area;
+#else
goto bad_area;
+#endif
+ }
#else
pte_t *ptep;
pmd_t *pmdp;
--
1.5.0.3
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