Messages in this thread | | | Date | Tue, 19 Dec 2023 18:55:35 +0100 | Subject | Re: [PATCH] x86/callthunks: Fix some potential string truncation in callthunks_debugfs_init() | From | Christophe JAILLET <> |
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Le 19/12/2023 à 12:02, Sohil Mehta a écrit : > On 12/17/2023 2:31 PM, Christophe JAILLET wrote: >> When compiled with W=1, we get: >> arch/x86/kernel/callthunks.c: In function ‘callthunks_debugfs_init’: >> arch/x86/kernel/callthunks.c:394:35: error: ‘%lu’ directive writing between 1 and 10 bytes into a region of size 7 [-Werror=format-overflow=] >> 394 | sprintf(name, "cpu%lu", cpu); >> | ^~~ >> arch/x86/kernel/callthunks.c:394:31: note: directive argument in the range [0, 4294967294] >> 394 | sprintf(name, "cpu%lu", cpu); >> | ^~~~~~~~ >> arch/x86/kernel/callthunks.c:394:17: note: ‘sprintf’ output between 5 and 14 bytes into a destination of size 10 >> 394 | sprintf(name, "cpu%lu", cpu); >> | >> >> So, give some more space to 'name' to silence the warning. > > It might be useful to specify that "some more space" hasn't been > arbitrarily decided. It took me a few minutes to figure that out. > > With the max cpu number being 4294967294 with 10 characters, a total of > 14 chars would be enough to print "cpu%lu".
From my POV, it is what the gcc warning already says, but I (or anyone else) can tweak the wording to make it more explicit.
Let me know if you want a v2.
CJ
> > >> (and fix the issue should a lucky one have a config with so many >> CPU!) >> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> >> --- >> arch/x86/kernel/callthunks.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> > > Apart from that, please feel free to add: > > Reviewed-by: Sohil Mehta <sohil.mehta@intel.com> > >> diff --git a/arch/x86/kernel/callthunks.c b/arch/x86/kernel/callthunks.c >> index cf7e5be1b844..26182a7d12b3 100644 >> --- a/arch/x86/kernel/callthunks.c >> +++ b/arch/x86/kernel/callthunks.c >> @@ -388,7 +388,7 @@ static int __init callthunks_debugfs_init(void) >> dir = debugfs_create_dir("callthunks", NULL); >> for_each_possible_cpu(cpu) { >> void *arg = (void *)cpu; >> - char name [10]; >> + char name[14]; >> >> sprintf(name, "cpu%lu", cpu); >> debugfs_create_file(name, 0644, dir, arg, &dfs_ops); > > >
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