| Message ID | 20240626074339.2820381-1-make24@iscas.ac.cn (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | xen: Fix null pointer dereference in xen_init_lock_cpu() | expand |
On 26.06.2024 09:43, Ma Ke wrote: > kasprintf() is used for formatting strings and dynamically allocating > memory space. If memory allocation fails, kasprintf() will return NULL. > We should add a check to ensure that failure does not occur. > > Fixes: d5de8841355a ("x86: split spinlock implementations out into their own files") > Signed-off-by: Ma Ke <make24@iscas.ac.cn> > --- > Found this error through static analysis. > --- > arch/x86/xen/spinlock.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c > index 5c6fc16e4b92..fe3cd95c1604 100644 > --- a/arch/x86/xen/spinlock.c > +++ b/arch/x86/xen/spinlock.c > @@ -75,6 +75,8 @@ void xen_init_lock_cpu(int cpu) > cpu, per_cpu(lock_kicker_irq, cpu)); > > name = kasprintf(GFP_KERNEL, "spinlock%d", cpu); > + if (!name) > + return; > per_cpu(irq_name, cpu) = name; > irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR, > cpu, While yes, error checking would better be added here, this isn't enough. You're treating an easy to diagnose issue (at the point where the NULL would be attempted to be de-referenced) for a possibly more difficult to diagnose issue: Any such failure will also need propagating back up the call stack. Jan
On Wed, Jun 26, 2024 at 03:43:39PM +0800, Ma Ke wrote: > kasprintf() is used for formatting strings and dynamically allocating > memory space. If memory allocation fails, kasprintf() will return NULL. > We should add a check to ensure that failure does not occur. Did you also consider what happens to the machine if you omit the rest of this function at init? As is, it is *extremely* unlikely the machine will fail the allocation at boot (it has all the memory unused after all) and if for some mysterious reason it does fail, we get a nice bug halting the boot and telling us where shit hit fan. Now we silently continue with undefined state and will likely run into trouble later because we failed to setup things, like that irqhandler. At which point everybody will be needing to buy a new WTF'o'meter to figure out WTF happened to get in that insane position. > Fixes: d5de8841355a ("x86: split spinlock implementations out into their own files") > Signed-off-by: Ma Ke <make24@iscas.ac.cn> > --- > Found this error through static analysis. Just because your tool found something, doesn't mean you have to be a tool and also not think about things. Please use brain don't be a tool. > --- > arch/x86/xen/spinlock.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c > index 5c6fc16e4b92..fe3cd95c1604 100644 > --- a/arch/x86/xen/spinlock.c > +++ b/arch/x86/xen/spinlock.c > @@ -75,6 +75,8 @@ void xen_init_lock_cpu(int cpu) > cpu, per_cpu(lock_kicker_irq, cpu)); > > name = kasprintf(GFP_KERNEL, "spinlock%d", cpu); > + if (!name) > + return; > per_cpu(irq_name, cpu) = name; > irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR, > cpu, > -- > 2.25.1 >
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c index 5c6fc16e4b92..fe3cd95c1604 100644 --- a/arch/x86/xen/spinlock.c +++ b/arch/x86/xen/spinlock.c @@ -75,6 +75,8 @@ void xen_init_lock_cpu(int cpu) cpu, per_cpu(lock_kicker_irq, cpu)); name = kasprintf(GFP_KERNEL, "spinlock%d", cpu); + if (!name) + return; per_cpu(irq_name, cpu) = name; irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR, cpu,
kasprintf() is used for formatting strings and dynamically allocating memory space. If memory allocation fails, kasprintf() will return NULL. We should add a check to ensure that failure does not occur. Fixes: d5de8841355a ("x86: split spinlock implementations out into their own files") Signed-off-by: Ma Ke <make24@iscas.ac.cn> --- Found this error through static analysis. --- arch/x86/xen/spinlock.c | 2 ++ 1 file changed, 2 insertions(+)