| Message ID | a75900413bb8b1e556be690e9588a0f92e946a30.1665733883.git.houwenlong.hwl@antgroup.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: Reduce refcount if single_open() fails in kvm_mmu_rmaps_stat_open() | expand |
On Fri, Oct 14, 2022 at 03:55:11PM +0800, Hou Wenlong wrote: > Refcount is increased before calling single_open() in > kvm_mmu_rmaps_stat_open(), If single_open() fails, refcount should be > restored, otherwise the vm couldn't be destroyed. > > Fixes: 3bcd0662d66fd ("KVM: X86: Introduce mmu_rmaps_stat per-vm debugfs file") > Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com> > --- > arch/x86/kvm/debugfs.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c > index cfed36aba2f7..412ed1b341fa 100644 > --- a/arch/x86/kvm/debugfs.c > +++ b/arch/x86/kvm/debugfs.c > @@ -162,7 +162,12 @@ static int kvm_mmu_rmaps_stat_open(struct inode *inode, struct file *file) > if (!kvm_get_kvm_safe(kvm)) > return -ENOENT; > > - return single_open(file, kvm_mmu_rmaps_stat_show, kvm); > + if (single_open(file, kvm_mmu_rmaps_stat_show, kvm)) { > + kvm_put_kvm(kvm); > + return -ENOMEM; > + } Thanks for fixing this. Would it be nicer to wire the single_open retval (even though it'll only fail with -ENOMEM with current code base)?
On Fri, Oct 14, 2022 at 10:09:55PM +0800, Peter Xu wrote: > On Fri, Oct 14, 2022 at 03:55:11PM +0800, Hou Wenlong wrote: > > Refcount is increased before calling single_open() in > > kvm_mmu_rmaps_stat_open(), If single_open() fails, refcount should be > > restored, otherwise the vm couldn't be destroyed. > > > > Fixes: 3bcd0662d66fd ("KVM: X86: Introduce mmu_rmaps_stat per-vm debugfs file") > > Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com> > > --- > > arch/x86/kvm/debugfs.c | 7 ++++++- > > 1 file changed, 6 insertions(+), 1 deletion(-) > > > > diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c > > index cfed36aba2f7..412ed1b341fa 100644 > > --- a/arch/x86/kvm/debugfs.c > > +++ b/arch/x86/kvm/debugfs.c > > @@ -162,7 +162,12 @@ static int kvm_mmu_rmaps_stat_open(struct inode *inode, struct file *file) > > if (!kvm_get_kvm_safe(kvm)) > > return -ENOENT; > > > > - return single_open(file, kvm_mmu_rmaps_stat_show, kvm); > > + if (single_open(file, kvm_mmu_rmaps_stat_show, kvm)) { > > + kvm_put_kvm(kvm); > > + return -ENOMEM; > > + } > > Thanks for fixing this. Would it be nicer to wire the single_open retval > (even though it'll only fail with -ENOMEM with current code base)? > I agree, it would be nicer to return the single_open() retval directly. I just follow how failure of simple_attr_open() is handled in kvm_debugfs_open(), but I think it should be changed too. > -- > Peter Xu
diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c index cfed36aba2f7..412ed1b341fa 100644 --- a/arch/x86/kvm/debugfs.c +++ b/arch/x86/kvm/debugfs.c @@ -162,7 +162,12 @@ static int kvm_mmu_rmaps_stat_open(struct inode *inode, struct file *file) if (!kvm_get_kvm_safe(kvm)) return -ENOENT; - return single_open(file, kvm_mmu_rmaps_stat_show, kvm); + if (single_open(file, kvm_mmu_rmaps_stat_show, kvm)) { + kvm_put_kvm(kvm); + return -ENOMEM; + } + + return 0; } static int kvm_mmu_rmaps_stat_release(struct inode *inode, struct file *file)
Refcount is increased before calling single_open() in kvm_mmu_rmaps_stat_open(), If single_open() fails, refcount should be restored, otherwise the vm couldn't be destroyed. Fixes: 3bcd0662d66fd ("KVM: X86: Introduce mmu_rmaps_stat per-vm debugfs file") Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com> --- arch/x86/kvm/debugfs.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)