| Message ID | 20241104192120.75841-1-bjorn@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [kvmtool] riscv: Pass correct size to snprintf() | expand |
On Mon, Nov 04, 2024 at 08:21:19PM +0100, Björn Töpel wrote: > From: Björn Töpel <bjorn@rivosinc.com> > > The snprintf() function does not get the correct size argument passed, > when the FDT ISA string is built. Instead of adjusting the size for > each extension, the full size is passed for every iteration. Doing so > will make __snprinf_chk() bail out on glibc. > > Adjust size for each iteration. > > Fixes: 8aff29e1dafe ("riscv: Append ISA extensions to the device tree") > Signed-off-by: Björn Töpel <bjorn@rivosinc.com> > --- > riscv/fdt.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/riscv/fdt.c b/riscv/fdt.c > index 8189601f46de..85c8f95604f6 100644 > --- a/riscv/fdt.c > +++ b/riscv/fdt.c > @@ -157,7 +157,7 @@ static void generate_cpu_nodes(void *fdt, struct kvm *kvm) > isa_info_arr[i].name); > break; > } > - pos += snprintf(cpu_isa + pos, CPU_ISA_MAX_LEN, "_%s", > + pos += snprintf(cpu_isa + pos, CPU_ISA_MAX_LEN - pos, "_%s", Just above this we confirm strlen(isa_info_arr[i].name) + pos + 1 is less than CPU_ISA_MAX_LEN, which means we should be able to use anything for size which is greater than or equal to strlen(isa_info_arr[i].name) + 1, as snprintf won't write more anyway. But, it's understandable that __snprinf_chk doesn't know that. > isa_info_arr[i].name); > } > cpu_isa[pos] = '\0'; Not part of this patch, but part of the context, so I'll comment on it anyway, this '\0' assignment could be removed. It looks like it's a left over from commit 7c9aac003925 ("riscv: Generate FDT at runtime for Guest/VM") which could have been removed with commit 8aff29e1dafe ("riscv: Append ISA extensions to the device tree") Anyway, Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Thanks, drew
On Mon, 04 Nov 2024 20:21:19 +0100, Björn Töpel wrote: > The snprintf() function does not get the correct size argument passed, > when the FDT ISA string is built. Instead of adjusting the size for > each extension, the full size is passed for every iteration. Doing so > will make __snprinf_chk() bail out on glibc. > > Adjust size for each iteration. > > [...] Applied to kvmtool (master), thanks! [1/1] riscv: Pass correct size to snprintf() https://git.kernel.org/will/kvmtool/c/574bd7b432ec Cheers,
diff --git a/riscv/fdt.c b/riscv/fdt.c index 8189601f46de..85c8f95604f6 100644 --- a/riscv/fdt.c +++ b/riscv/fdt.c @@ -157,7 +157,7 @@ static void generate_cpu_nodes(void *fdt, struct kvm *kvm) isa_info_arr[i].name); break; } - pos += snprintf(cpu_isa + pos, CPU_ISA_MAX_LEN, "_%s", + pos += snprintf(cpu_isa + pos, CPU_ISA_MAX_LEN - pos, "_%s", isa_info_arr[i].name); } cpu_isa[pos] = '\0';