d17b664173
With KCFLAGS="-O3", I was able to trigger a fortify-source memcpy() overflow panic on set_vi_srs_handler(). Although O3 level is not supported in the mainline, under some conditions that may've happened with any optimization settings, it's just a matter of inlining luck. The panic itself is correct, more precisely, 50/50 false-positive and not at the same time. From the one side, no real overflow happens. Exception handler defined in asm just gets copied to some reserved places in the memory. But the reason behind is that C code refers to that exception handler declares it as `char`, i.e. something of 1 byte length. It's obvious that the asm function itself is way more than 1 byte, so fortify logics thought we are going to past the symbol declared. The standard way to refer to asm symbols from C code which is not supposed to be called from C is to declare them as `extern const u8[]`. This is fully correct from any point of view, as any code itself is just a bunch of bytes (including 0 as it is for syms like _stext/_etext/etc.), and the exact size is not known at the moment of compilation. Adjust the type of the except_vec_vi_*() and related variables. Make set_handler() take `const` as a second argument to avoid cast-away warnings and give a little more room for optimization. Signed-off-by: Alexander Lobakin <alobakin@pm.me> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
31 lines
941 B
C
31 lines
941 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _MIPS_SETUP_H
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#define _MIPS_SETUP_H
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#include <linux/types.h>
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#include <uapi/asm/setup.h>
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extern void prom_putchar(char);
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extern void setup_early_printk(void);
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#ifdef CONFIG_EARLY_PRINTK_8250
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extern void setup_8250_early_printk_port(unsigned long base,
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unsigned int reg_shift, unsigned int timeout);
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#else
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static inline void setup_8250_early_printk_port(unsigned long base,
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unsigned int reg_shift, unsigned int timeout) {}
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#endif
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void set_handler(unsigned long offset, const void *addr, unsigned long len);
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extern void set_uncached_handler(unsigned long offset, void *addr, unsigned long len);
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typedef void (*vi_handler_t)(void);
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extern void *set_vi_handler(int n, vi_handler_t addr);
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extern void *set_except_vector(int n, void *addr);
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extern unsigned long ebase;
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extern unsigned int hwrena;
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extern void per_cpu_trap_init(bool);
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extern void cpu_cache_init(void);
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#endif /* __SETUP_H */
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