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drm/i915: Fix buffer overflow in dsi_calc_mnp() 

smatch complain:

	drivers/gpu/drm/i915/intel_dsi_pll.c:101 dsi_calc_mnp() error: buffer
	overflow 'lfsr_converts' 39 <= 4294967234

and looks justified in doing so.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1467470166-31717-7-git-send-email-chris@chris-wilson.co.uk
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
This commit is contained in:
Chris Wilson 2016-07-02 15:36:04 +01:00
parent ebe69dd366
commit 1bbea16a73
1 changed files with 9 additions and 8 deletions
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17
drivers/gpu/drm/i915/intel_dsi_pll.c
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@ -55,12 +55,10 @@ static int dsi_calc_mnp(struct drm_i915_private *dev_priv,
struct intel_crtc_state *config,
int target_dsi_clk)
{
unsigned int calc_m = 0, calc_p = 0;
unsigned int m_min, m_max, p_min = 2, p_max = 6;
unsigned int m, n, p;
int ref_clk;
int delta = target_dsi_clk;
u32 m_seed;
unsigned int calc_m, calc_p;
int delta, ref_clk;
/* target_dsi_clk is expected in kHz */
if (target_dsi_clk < 300000 || target_dsi_clk > 1150000) {
@ -80,6 +78,10 @@ static int dsi_calc_mnp(struct drm_i915_private *dev_priv,
m_max = 92;
}
calc_p = p_min;
calc_m = m_min;
delta = abs(target_dsi_clk - (m_min * ref_clk) / (p_min * n));
for (m = m_min; m <= m_max && delta; m++) {
for (p = p_min; p <= p_max && delta; p++) {
/*
@ -97,11 +99,10 @@ static int dsi_calc_mnp(struct drm_i915_private *dev_priv,
}
/* register has log2(N1), this works fine for powers of two */
n = ffs(n) - 1;
m_seed = lfsr_converts[calc_m - 62];
config->dsi_pll.ctrl = 1 << (DSI_PLL_P1_POST_DIV_SHIFT + calc_p - 2);
config->dsi_pll.div = n << DSI_PLL_N1_DIV_SHIFT |
m_seed << DSI_PLL_M1_DIV_SHIFT;
config->dsi_pll.div =
(ffs(n) - 1) << DSI_PLL_N1_DIV_SHIFT |
(u32)lfsr_converts[calc_m - 62] << DSI_PLL_M1_DIV_SHIFT;
return 0;
}