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random: round-robin registers as ulong, not u32

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commit da3951ebdcd1cb1d5c750e08cd05aee7b0c04d9a upstream.

When the interrupt handler does not have a valid cycle counter, it calls
get_reg() to read a register from the irq stack, in round-robin.
Currently it does this assuming that registers are 32-bit. This is
_probably_ the case, and probably all platforms without cycle counters
are in fact 32-bit platforms. But maybe not, and either way, it's not
quite correct. This commit fixes that to deal with `unsigned long`
rather than `u32`.

Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jason A. Donenfeld 2022-02-22 13:46:10 +01:00 committed by Greg Kroah-Hartman
parent 5064550d42
commit c47f215ab3
1 changed files with 3 additions and 3 deletions
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6
drivers/char/random.c
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@ -1261,15 +1261,15 @@ int random_online_cpu(unsigned int cpu)
} }
#endif #endif
static u32 get_reg(struct fast_pool *f, struct pt_regs *regs) static unsigned long get_reg(struct fast_pool *f, struct pt_regs *regs)
{ {
u32 *ptr = (u32 *)regs; unsigned long *ptr = (unsigned long *)regs;
unsigned int idx; unsigned int idx;
if (regs == NULL) if (regs == NULL)
return 0; return 0;
idx = READ_ONCE(f->reg_idx); idx = READ_ONCE(f->reg_idx);
if (idx >= sizeof(struct pt_regs) / sizeof(u32)) if (idx >= sizeof(struct pt_regs) / sizeof(unsigned long))
idx = 0; idx = 0;
ptr += idx++; ptr += idx++;
WRITE_ONCE(f->reg_idx, idx); WRITE_ONCE(f->reg_idx, idx);