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| author | Michael Ellerman <mpe@ellerman.id.au> | 2023-01-30 02:47:07 +0100 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2023-01-31 11:37:36 +0100 |
| commit | 7294194b47e994753a86eee8cf1c61f3f36458a3 (patch) | |
| tree | 5aca0a12aa6ed6790dde03ab033c78c260aae45b /arch | |
| parent | powerpc/imc-pmu: Revert nest_init_lock to being a mutex (diff) | |
| download | linux-7294194b47e994753a86eee8cf1c61f3f36458a3.tar.xz linux-7294194b47e994753a86eee8cf1c61f3f36458a3.zip | |
powerpc/kexec_file: Fix division by zero in extra size estimation
In kexec_extra_fdt_size_ppc64() there's logic to estimate how much
extra space will be needed in the device tree for some memory related
properties.
That logic uses the size of RAM divided by drmem_lmb_size() to do the
estimation. However drmem_lmb_size() can be zero if the machine has no
hotpluggable memory configured, which is the case when booting with qemu
and no maxmem=x parameter is passed (the default).
The division by zero is reported by UBSAN, and can also lead to an
overflow and a warning from kvmalloc, and kdump kernel loading fails:
WARNING: CPU: 0 PID: 133 at mm/util.c:596 kvmalloc_node+0x15c/0x160
Modules linked in:
CPU: 0 PID: 133 Comm: kexec Not tainted 6.2.0-rc5-03455-g07358bd97810 #223
Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1200 0xf000005 of:SLOF,git-dd0dca pSeries
NIP: c00000000041ff4c LR: c00000000041fe58 CTR: 0000000000000000
REGS: c0000000096ef750 TRAP: 0700 Not tainted (6.2.0-rc5-03455-g07358bd97810)
MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 24248242 XER: 2004011e
CFAR: c00000000041fed0 IRQMASK: 0
...
NIP kvmalloc_node+0x15c/0x160
LR kvmalloc_node+0x68/0x160
Call Trace:
kvmalloc_node+0x68/0x160 (unreliable)
of_kexec_alloc_and_setup_fdt+0xb8/0x7d0
elf64_load+0x25c/0x4a0
kexec_image_load_default+0x58/0x80
sys_kexec_file_load+0x5c0/0x920
system_call_exception+0x128/0x330
system_call_vectored_common+0x15c/0x2ec
To fix it, skip the calculation if drmem_lmb_size() is zero.
Fixes: 2377c92e37fe ("powerpc/kexec_file: fix FDT size estimation for kdump kernel")
Cc: stable@vger.kernel.org # v5.12+
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230130014707.541110-1-mpe@ellerman.id.au
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/kexec/file_load_64.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c index af8854f9eae3..19d084682bc2 100644 --- a/arch/powerpc/kexec/file_load_64.c +++ b/arch/powerpc/kexec/file_load_64.c @@ -989,10 +989,13 @@ unsigned int kexec_extra_fdt_size_ppc64(struct kimage *image) * linux,drconf-usable-memory properties. Get an approximate on the * number of usable memory entries and use for FDT size estimation. */ - usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) + - (2 * (resource_size(&crashk_res) / drmem_lmb_size()))); - - extra_size = (unsigned int)(usm_entries * sizeof(u64)); + if (drmem_lmb_size()) { + usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) + + (2 * (resource_size(&crashk_res) / drmem_lmb_size()))); + extra_size = (unsigned int)(usm_entries * sizeof(u64)); + } else { + extra_size = 0; + } /* * Get the number of CPU nodes in the current DT. This allows to |