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    SubjectRE: [PATCH, net-next] net: ethernet: freescale: fix false-positive string overflow warning
    Date
    From: Arnd Bergmann <arnd@arndb.de> Sent: 2018年5月28日 23:50
    > While compile-testing on arm64 with gcc-8.1, I ran into a build diagnostic:
    >
    > drivers/net/ethernet/freescale/fec_main.c: In function 'fec_probe':
    > drivers/net/ethernet/freescale/fec_main.c:3517:25: error: '%d' directive
    > writing between 1 and 10 bytes into a region of size 5
    > [-Werror=format-overflow=]
    > sprintf(irq_name, "int%d", i);
    > ^~
    > drivers/net/ethernet/freescale/fec_main.c:3517:21: note: directive
    > argument in the range [0, 2147483646]
    > sprintf(irq_name, "int%d", i);
    > ^~~~~~~
    > drivers/net/ethernet/freescale/fec_main.c:3517:3: note: 'sprintf' output
    > between 5 and 14 bytes into a destination of size 8
    > sprintf(irq_name, "int%d", i);
    > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    >
    > It appears this has never shown on ppc32 or arm32 for an unknown
    > reason, but now gcc fails to identify that the 'irq_cnt' loop index has an
    > upper bound of 3, and instead uses a bogus range.
    >
    > To work around the warning, this changes the sprintf to snprintf with the
    > correct buffer length.
    >
    > Fixes: 78cc6e7ef957 ("net: ethernet: freescale: Allow FEC with
    > COMPILE_TEST")
    > Signed-off-by: Arnd Bergmann <arnd@arndb.de>

    Acked-by: Fugang Duan <fugang.duan@nxp.com>

    > ---
    > drivers/net/ethernet/freescale/fec_main.c | 2 +-
    > 1 file changed, 1 insertion(+), 1 deletion(-)
    >
    > diff --git a/drivers/net/ethernet/freescale/fec_main.c
    > b/drivers/net/ethernet/freescale/fec_main.c
    > index ab7521c04eb2..c729665107f5 100644
    > --- a/drivers/net/ethernet/freescale/fec_main.c
    > +++ b/drivers/net/ethernet/freescale/fec_main.c
    > @@ -3514,7 +3514,7 @@ fec_probe(struct platform_device *pdev)
    > goto failed_init;
    >
    > for (i = 0; i < irq_cnt; i++) {
    > - sprintf(irq_name, "int%d", i);
    > + snprintf(irq_name, sizeof(irq_name), "int%d", i);
    > irq = platform_get_irq_byname(pdev, irq_name);
    > if (irq < 0)
    > irq = platform_get_irq(pdev, i);
    > --
    > 2.9.0

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