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powerpc/xive: make xive IPI allocation NULL-safe

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__GFP_NOFAIL should not be used in new code [1].  xive_init_ipis()
allocates the xive_ipis array with __GFP_NOFAIL, which makes the
subsequent NULL check unreachable dead code.

Remove __GFP_NOFAIL so the allocation can fail, and make all xive_ipis
access paths NULL-safe:

- Return XIVE_BAD_IRQ from xive_ipi_cpu_to_irq() when xive_ipis is NULL.
- Set xive_ipis to NULL after kfree() in the error path to prevent
  use-after-free.
- Guard xive_setup_cpu_ipi() and xive_cleanup_cpu_ipi() against
  xive_ipi_irq == XIVE_BAD_IRQ to avoid dereferencing an uninitialized
  or already-freed xive_ipis array.

No functional change when allocation succeeds.

Link: https://lore.kernel.org/all/20260725202632.dcb325658896a470df91cf57@linux-foundation.org/ [1]
Fixes: 7dcc37b3ef ("powerpc/xive: Map one IPI interrupt per node")
Signed-off-by: Gou Hao <gouhao@uniontech.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Cédric Le Goater <clg@kaod.org>
Suggested-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Reviewed-by: Wentao Guan <guanwentao@uniontech.com>
Reviewed-by: jiazhenyuan <jiazhenyuan@uniontech.com>
Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260727104215.184786-2-gouhao@uniontech.com
This commit is contained in:
Gou Hao
2026-07-27 18:42:11 +08:00
committed by Madhavan Srinivasan
parent fa40f9dbdd
commit f068fca7e8
1 changed files with 10 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
arch/powerpc/sysdev/xive/common.c
View File

@@ -74,6 +74,8 @@ static struct xive_ipi_desc {
*/
static unsigned int xive_ipi_cpu_to_irq(unsigned int cpu)
{
if (!xive_ipis)
return XIVE_BAD_IRQ;
return xive_ipis[early_cpu_to_node(cpu)].irq;
}
#endif
@@ -1132,8 +1134,7 @@ static int __init xive_init_ipis(void)
if (!ipi_domain)
goto out_free_fwnode;
xive_ipis = kzalloc_objs(*xive_ipis, nr_node_ids,
GFP_KERNEL | __GFP_NOFAIL);
xive_ipis = kzalloc_objs(*xive_ipis, nr_node_ids, GFP_KERNEL);
if (!xive_ipis)
goto out_free_domain;
@@ -1158,6 +1159,7 @@ static int __init xive_init_ipis(void)
out_free_xive_ipis:
kfree(xive_ipis);
xive_ipis = NULL;
out_free_domain:
irq_domain_remove(ipi_domain);
out_free_fwnode:
@@ -1190,6 +1192,9 @@ static int xive_setup_cpu_ipi(unsigned int cpu)
pr_debug("Setting up IPI for CPU %d\n", cpu);
if (xive_ipi_irq == XIVE_BAD_IRQ)
return -EIO;
xc = per_cpu(xive_cpu, cpu);
/* Check if we are already setup */
@@ -1234,6 +1239,9 @@ noinstr static void xive_cleanup_cpu_ipi(unsigned int cpu, struct xive_cpu *xc)
/* Disable the IPI and free the IRQ data */
if (xive_ipi_irq == XIVE_BAD_IRQ)
return;
/* Already cleaned up ? */
if (xc->hw_ipi == XIVE_BAD_IRQ)
return;